Beginner Road Track Racing: Feedback on Engine Options Wanted

30 year SCCA racer... my class was GT-4 / also GT-lite . not a Mopar unfortunately but a full tube framed 200SX.
My most fun was when I had a street based motor in a race chassis, it took very little maintenance , ran on pump gas and I got tons of track time.
The biggest enemy of a racer is seat time, if you cant go fast with 100 hp on a road course 600 wont do you any good. you have to learn to drive and practice.
Track time and tires are expensive , spend your first money on a good chassis (full cage) and big brakes , I recommend an FIA homologated fuel cell and it may be required by some sanctioning bodies.

contact me by message I'll be more than happy to give you directions
thanks for your input and offer to contact you. I agree that I don't want to start off seeking the most power out of the engine since I want to get used to things and work my way up.