Taking into consideration the 4.11 gears and 4 speed (the m21 is the wide ratio box, right?), I would not be afraid to use the 282H06 in this application, but I wouldn't want to use anything bigger with 9.0-1 compression. My concern with using pressed in studs with the larger XE cams is their aggressive lobes *might* start pulling pressed in studs out of the heads. Granted, I am using an XE268 with matching springs with a set of vortec heads with press in studs and it has worked great for 7+ years now, but these was brand new heads...not 40 year old castings. The XE268 pulls great to a little under 6K rpms with a performer rpm intake and good exhaust.
Actually, after thinking about it for a while, I would use the comp cams 275 dual energy hydraulic. It is 219/
[email protected], .462/.482 lift, on a 110 lsa. The lobes are a bit milder (easier break in and longer valvespring life, plus less stress on the studs), the 10* intake/exhaust difference will provide a wide powerband, and the 275* intake duration will provide a healthy idle and still provide good street manners. This setup shouldn't need more than 89 octane fuel, and should pull hard from 2000-6000 rpms. Plus, you don't have the XE lines noisy valvetrain...thats a big plus to me even though they do work great.
Normally I wouldn't suggest a cam this size for a 9.0-1 engine, but those gears and 4 speed will easily overcome the torque loss on the low end from lack of cylinder pressure. And don't get me wrong...the XE274 will work, but personally I would like to see .5 to 1 more point of compression and screw in studs for a cam that size. Everybody has their own way of doing things though :thumbsup: Just be sure you use matching valve springs with whatever cam you choose.