318 MAX fuel economy builds?

So what I'm thinking for starters is taking an old 78 318 I have, deburr the whole block and put glytal on the inside for better oil return increasing longevity, maybe find a good set of 302 heads and do a little cleaning up in the bowl area and valve guide area. Get a Isky More-A-Mile camshaft paired with a good set of flat top hypereutectic flat top pistons (maybe in the 10.5:1 area?) I managed to find an Edelbrock SP2P 2 barrel intake so that decreases intake weight and helps with low end power as well, maybe headers? Maybe not I'll need some input on the exhaust aspect, a Stromberg WWC 2 barrel I have from a 361 big block with maybe OD auto trans and 3.55s out back? Rough thoughts I can go further into detail but thoughts? Inputs?