I have had both a stock block 331 SBF, and currently have a "big bore" 347, both pump gas usable, flat top pistons, with AFR 185 heads. The 331 made 487 HP, and ran mid to low 10s in the 1/4 mile, for a couple of years before it split the main bearing area of the factory 5.0 roller block. It had a solid flat tappet cam, and never went over 7000 RPM. My current 347,made 528 HP, has a 4.125" bore Dart block. Both engines used 3.25" stroke cranks, the 331 was a cast Eagle, with 28 oz imbalance, the 347 has an internal balanced steel crank, and a hyd. roller cam, that I shift at 7000 RPM, and hits 7200 across the finish line. Considering the use of a stock block limits you to a 4.03" bore , that means you will be using a 3.4" stroke. With the longer stroke causing more cylinder side loading, and wanting to turn 7500 RPM, makes me doubtful that a stock block will be very long lived, if you actually plan to twist it that high very often.