I’m not really the small block Mopar authority...... unless it finds itself here for freshening.
On that RPM headed motor...... it wasn’t pump gas. Iirc, about 11.7:1.
Heads flowed 285-ish(I’ve never figured out where the 300+ magic is with those), cam was like 264/268-108, .640-ish, 1.5 rockers.
It was built using an R block though...... 4.100 x 4.00.
Flow numbers between your numbers are pretty close til after .500 on the intake side.