Not looking fo high horsepower out of her but like I said this is my daily. If I got 50-100 horse I would be stoked. What I’m after is just a little more pep in her step. I have access to a 351, and picking up a spare 305 and 4 speed in a week or so. What I was planning to do is go through the spare block prob balance the crank just to get it to rev a bit higher. Slap efi and eBay turbo on it. Then yank my original block and give it some love. If I blow up the spare then so be it... wasn’t my original engine.
If your talking about reliability stuff though. Just basics or stuff for these particular 60 degree blocks?
Upgrading the rods(custom), the oiling system, the bearings(custom), the pistons(custom) (unless you can find some 4 ring forklift ones), the lifters/pushrods/rockers, intake and fuel system, cam(custom), and a good amount of head, crank, and block work.
Now if you dont care about the engine just do what I have done with half a dozen smog bbc's and run rich then blow 4 to 6psi through the stock restricted (peanut) heads. Your going to make some power(if you don't wash the walls). But only want to do it in brief periods because it does not take much to destroy factory stuff and turning up the psi higher then you know you should will happen. Followed by busted rods or pistons.
The "safer" and frankly cleaner way as it leaves the block looking stock is to increase the NA compression. You really should still upgrade a few things here. But you will have a tune for one rpm curve letting you have a proper ratio at all times instead of a compromised one with a blow through setup.
Now I dont like to make custom parts. I will however take a existing factory part and machine it slightly. Rods come to mind. There are several sets of factory forged rods out. You may be able to measure your rods and find a modern forged set that is close. Change the pin then install a "better" piston that matches your bore.
The 305 may have parts from a dozen diffrent brands. But you will be able to get parts even if you need to machine those parts slightly to make them work.
One of those things once you lay out the disassembled parts, take measurments, and then spend weeks searching and a few more weeks machining(you may destroy a few) then you will have a "custom" say Toyota rods and forklift(4 ring) pistons, with sbc lifters, Ford valves, and a oil pump out of a cummins.
You know. Old school hotrodding stuff making power by making things work(and a ton of math/machining).