Bob, what you have read above is true.
As for me , I didn't have crossmember issues. I got mine from 5speed.com. Thats where both trans came from.
Croosmember is not like others I have seen , its a basic thick , flat , bat wing looking cross member with curves to go over exhaust.
As for alignment, it does make a difference. to the trans as well as vibration and warranty. This trans is not like a muncie , having a front ball bearing on the main shaft. Tremec , uses and cone/cup type bearing , and is shimed in at the factory. This bearing requires you to have that center of you crank to center of mainshaft with in .005. Its critical. You might want to ask your vendor for a better bellhousing than stock 403 or 621.
Mine was a Lakewood scatter shield and it was off as I mentioned. A new housing from Motorsports, took care of the alignment, but you need to check it any way. Some where on this site a member has a Brown tool, that is a go/no go tool I believe the loner tool was cheap rental. Not sure who had it but its out there. Maybe your vendor can help you with this, they may have a loner. Maybe your vendor has a rental.
Another thing, you need to buy the speedo adapter as well as a speedo cable. I had an issue using the stock cable, it allowed trans oil to wick up into the speedo and drips on my leg. I spoke to American Powertrain about this, they had the correct cable. Not sure if it had to do with the way speedo cable chain is wrapped or not , but I had no more problems and I drive PowerTours, thats abotu 3000 miles round trip.
As for the shifter, I kept the stock shifter , I modified my Hurst shifter stick buy drilling out the holes to accept the bolts that Tremec shifter stub was. The threads were metric.
I don't have a console as I have a base coupe, Could not afford all the bells and whistles these cars came with, I ordered a plain Z28 coupe , with stock interior.
Again, I would go with American as a kit, everything that your need , they sell.
If you need pictures, I have my car up on stands for winter and about to take it down. I can send you some but tell me what area are you looking for.
I didn't have to cut out my stock shifter hole as the trans shifter stub came right up into it.
Brown tool I was referring to is this.