As far as holding up to 490hp, I doubt a stockish Saginaw will do it. Your best bet is to find a M22 Muncie 4-speed. I will be installing a muncie in the road race project behind a 500-600 hp circle track engine. The M22 was used behind some of those monster big blocks of the late 60's and early 70's. As far as a stock option to hold that kind of power, the M22 will be the closest to being able to accomplish it. And there are tons of parts out there to beef them up even more at respectable prices. Of course for my application, the muncie will be built to withstand the harshest conditions imaginable. But for the street and occasional track use, a stock M22 with a fresh rebuild would be ideal for you. You could even find a M21 or M20 muncie, but they arent rated as high for power/torque capacity, but the case are identical throughout the range and can be built with M22 internals.
