If choosing between stroking a 5.7l to 383 (350Hp / 400 ft lbs) and upgrading cam, rockers, etc to keep as 5.7l, which is best way to go? Alpha is Gen II & boat approx 3200 lbs. Do not want to trash the drive...

Merc used Alphas with their 330 big blocks for a time and they did OK as long as you didn't try to log too much air-time or pull impressive hole shots. So I think a built small block would be fine as long as you drive intelligently. It was big torque that killed Alphas. DO install a drive shower, however! --- Jer

I am going to put some power through an alpha too,I guess we'll see how they hold up!!

I've been turning an Alpha behind a small gas turbine engine for over 100 hrs, no problem. 320 hp 6000 rpm. Just back off when you catch air, ( the vertical shaft likes to snap) and take it esay on hole shots ( the upper gearsets strip out).
Shower a must and synthetic oil. My drive guy, shims the bearings a little tighter so the rollers don't "skate" across the races.