Re: Ď71 Chevelle 350, looking for direction
My opinion...If its an all original numbers matching car, personally I would keep that aspect intact. Get the transmission rebuilt, crisping up the shifts. New converter (stock, or just a smidge above, nothing crazy). Rebuild the engine with minor modifications. If the cylinder bores are good you can just cut the ridge and hone the cylinders with new rings, or go .030 over with a new set of pistons/rings. Get the heads/valves done with new guides that'll work on today's pump gas and new springs to match a mild cam. A kit like the K12-238-2 from Competition Cams would include a good cam for your application and includes springs, lifters, timing gears/chain, seals, and spring retainers and will be under $350. Upgrade the distributor to electronic ignition.
Now here is the only thing I would change. Edelbrock Performer manifold, a Holley 600 with vacuum secondaries (or if you already have a 4bbl Q-Jet, get that rebuilt and tuned), and a set of headers with dual exhaust. (Keep ALL the original parts you replace and store them away for safe keeping, and if the stock exhaust is good don't let some butcher hack it up and scrap it, keep that too)
Make sure to dial in (degree) the cam and gasket match the intake ports on the heads and intake.
You'll have a basically unmolested "numbers matching" Malibu (getting harder to find) that you'll be able to drive anywhere (assuming the chassis/suspension is all good to go) and still have some lead footed fun for probably WAY under your budget.
Again, my opinion.
'71 SS 350
3rd and 6th owner
2017 Harley Davidson Road Glide Ultra