383 2bbl vs 383 4 bbl

All 2 bbl 383's had dished flat top pistons. Only the '68 and '69 383 4 bbl, hp and non hp had the tallest piston to deck height. It appears that your H code 383 is an hp engine. So it would have the following additional differences to the 383 2bbl:

crankshaft windage tray,
hp cam(same as 440 hp),
hp exhaust manifolds,
hp single valve springs with inner damper,
tri metal main bearings(383 2bbl tended to have babitt mains)
but I have done several 2bbl to 4 bbl intake/carb swaps on 383's and they run
just fine, David.