Welcome to the site!
Good idea on changing up the originality of the cutlass. If you want good ideas on interior change up check out some build threads there are plenty of good ideas out there. I was in the same boat as you, but changed up my interior grant makes universal steering wheels wooden ones are cool. If you have the oh so common bench seat and column shift, go find a floor shift combo. ( you said 70's 442) dont know how far you want to go but its easy to get carried away.
If you want "more" out of a 305? Or 307?
You probably have a 307 olds. If you do the most id do is add a few hp tweaks. Like higher ratio rockers, add a new distributor, headers and a tune up. Also suggest using a higher octane gasoline like 89