400 into 65 valiant

streetmaster used to (may still have) custom motor mounts for this. I have a set for a future project. i understand that a B will fit with 68-70 HP ex manifolds. Trim the sloped firewall junction protrusion & wouldn't hurt to weld that now flat joint across for strength. also a good plan is to modify the crossmember so you can run dual ex without the one side pipe hanging too low. I ran a 727 with a SB in an early A & the trans just touched the sloped firewall protruding pinch weld joint & I under stand tolerances varied alot & some may clear & some need work. I have a bell to adapt a big block to a 904 which will elim the firewall issues tho the 904 will have to be build up more to handle the BB. this is all the info I've come up with for my way in the future build