383 Rev Limit question

You can (Or should be able to) get the iron heads done for less than Edelbrock heads. The new springs should be MoPars own. They have springs to match there cams.
P5249848 for .480 - .540 lift,
P2806077 for .500 - .610 lift.
Your lift of .509 with 1.6 rockers is; .54293333333333333..........
I'd run the second spring for more control with the 1.6 rockers.
Going the next valve size up is adviseable like mentioned above You really do not need a larger intake valve. A larger exhaust valve would be good. Have the machinest bowl port and gasket match the head.
The MP porting template for the B/RB stock head is P4120437
Also, DO NOT be bothered "Polishing" the head. It is sooo not needed. Save it for when your racing for the money with serious hardware on top.

IMO, dump the Team G and use ethier a RPM or M1 single plane intake.

The cams basic RPM range is 2600 - 6000 RPM's. Shift at 6200 and cross the finish line at 6500. for a beginer. Adjust shift points upwards at 200 rpm jumps to see how it performs in MPH and et. (Mostly et.)

You also mentioned that the previous owner only ran 111 octane. This would suggest it has indeed a very high compresion ratio and I think it nuts to run one. But! One of 2 things may happen here. Ethier it does indeed have a high ratio or the previous owner is an idiot who ran the 111 gas for no other reason but stupidness. (My fav excess, I like the smell of it.)

OH, your exhaust @ 2-1/2 is fine. 3 would be better, but it's not reall worth the $$$ to change unless your on the track with the like gear,stall, tire size/style/compound, car weight, etc.........