I have a 1970 Chevy 350 that came from a 1970 Impala. It is currently in my 1968 Camaro. The engine has around 3500 miles on it since the rebiuld. Here are the engine specs:

it is a 4 bolt main 350 bored .030 over it has new flat top pistons, reconditioned rods, polished std/std crank, double roller timing chain with a Summit Racing 1102 cam. The heads are "441" castings with all new guides, multi angle valve job & springs. The intake is an Edelbrock performer, with a 600 Holley carb and an new HEI ignition

There are no oil leaks and no smoke from the exhasut

Question:
I have to add about 3/4 quart of oil every 900 to 1000 miles. Is this normal for an older model 350 even though it is not leaking oil and all the gaskets are good?