If you have the 303 olds injector body they are easy to adapt to the Lincoln. I did it and It picked up 60 horse over the best factory manifold.But that was mechanical injection, not EfI
This guy can help you with adapting the Hilborn to EFI .
https://foxinjection.com/. Alkydiggers.com can also do it
I have a couple old Edmunds dual carb intakes that would be OK for a warmed up stock engine one is ported by JDC and flows enough to make 350 or 375 horse. Forget the roller cam the view is not worth the climb, unless you address a lot of other areas that would be expensive, and negatively affect street manners. In fact even flat tappet blanks are very hard to find.. Regrinding your stock core will serve you just fine..Spend your money on head work ,increasing compression, and improving the intake manifold.. 400hp is not an unreasonable goal. I made my own intake spacers.. That is a big chunk of aluminum to make it work, but work it does. I merely calculated how thick the spacer needed to be, put a 368 gasket on one side and traced out the pattern, Then the SBC gasket on the other side and scribed that . Drill the holes to mount spacer to block, then manifold to spacer... I had JDC do the finish work, line up the ports and shape them to match up side to side.. It works well, but you better have a lot of hood clearance