[Vintage 68]

What transmission (and what mods [stall/valve body type/etc...] if Auto)?
What type of extended use - Cruising, Competition % and type or ???
What RPM levels?

You'll need to lock in your desired CR range pretty tight before you can pick a cam that will work with it - or ... go the other way around, and pick a cam you like that fits your upper-end set-up and then go with the required CR to match ...
A cast BB crank is very reliable to @700+HP with common prep and assembly procedures for street performance use. The type of driveline and your desired RPM level will effect the crank choice even more than it's construction in many cases.
Your HP goals are pretty easy to reach with the right cam to go with your heads and bottom end.


The Mark IV will accept a roller with minimum mods - but type and use influence what is needed to use for both the block, heads and valve train.

You're usually fine calling a few manufactures and discussing your application with them and getting their recommendations.
You can then post their input (along with you needs) on here and let us comment on the plus/minus of each.

 

[Vintage 68]

Okay, 1st the driveline;
The M21's are very reliable transmission and able to handle 400~450HP very reliably, depending on tire and use ...
Since you'll do little to no competition with it, it may be fine if you aim for the lower of your goals and avoid any major shock-loading of the driveline - e.g. - hard launches with sticky tires and surfaces.
If you get into some spirited driving from time to time it may start to emit sounds that will clue you it has decided you've reached the limits of it's endurance and you'll be looking for a 'new' trans type
Same goes for that 10-bolt - I've put those HP levels into them for years and they have still given good service - BUT, it depends on the use and again 'shock-loads' to it. A few hard launches with good hook and/or mixed traction surfaces (one/both wheel(s) hooking and releasing in succession) it may not last as long as you hoped without some internal part and modifications.

6~6.5K RPM will not be an issue with well sellected valve train and internal parts - as long as you don't hold it there for long periods ...
With a Solid Roller you can raise that another .5~1K - but it's gonna have to be accompanied by better internals and valve trains stuff or if will become troublesome pretty quick ...
But - your heads are going to become the limiting factor here long before a cam runs out of 'poop' to go for more - some work with valve prep and minor port matching and bowl work will increase their ability to support some higher RPM flow.

Dropping the static CR and sellecting a cam with a better DCR will allow you to use lower level fuel octanes.
You are of course giving up some output with each of these mods, so you'll need to decide if HP or fuel selection is going to be the limiting factor for your build.
Most will stay under 10:1 for reliable street use and decent flexability with fuel.

I always 'freshen-up' the bottom-end when doing a build that is intended to increase the available HP fro reliablilty.
It's a very reasonable cost for the return ...
The Clevite-77 bearings are a very good choice - never have much trouble with them if they are matched to the application.
I almost always check and polish the crank when doing these type of builds - again, it's very cheap insurance to be sure it's not hiding an issue and make sure it gets the best shot at serving my needs for the build.

Cam drive should be kept pretty 'mundane' for street use :yes:
A 'Double-roller' is not normally necessary for street level valve train loads and use of one may be limited by cam choice on a Mark-IV BB, modern Gen. V-VI rollers will require use of a narrower chain for clearance.
A good quality major brand timing chain and gears can be just as strong and will live a long happy life in most cases.
The last thing I would recommend for a strickly street driven engine was "Gear Drive" (or most of them anyway).
Most common 'Speed-shop' Gear drives induce odd harmonics in the cam/valve train that tend to lessen the longevity of these in a short amount of street type driving.
They are also the cause of lots of oddities with some ignition systems resulting in unstable advance curves and spark issues.
If you wanted that 'Noise' - find another way to get it :yes:

Hope this helps some.