B-body B/RB hp manifold will fit on right side, but without milling it will also hit the right inner fender skirt if using factory bb a-body K-frame. I do not know if spool mount k-frame sits different?
That's interesting ....I wonder if a factory Big block K frame moves the engine over to the passenger side a bit to clear the drivers mount. ??
on a home fabbed K frame (former slant six K ) and modified Spool mount K the passenger side sits with about 1/4 to 1/2 inch clearance with an RB . of course every car is different with the tolerance.