225 performance upgrades without pulling engine

Breath easy in... breath easy out ...

Long runners provide more torque.
Shorter runners provide more top end HP.
The headers into a 2-1/2 inch exhaust and a long runner intake is what I would do for bolt on performance upgrades. FWIW, a small 4 bbl. carby isn’t a bad idea ether since your driving around on the primary side at approximately 200 if you can find an old Carter @ 400 cfm. A readily available 500 is easy to get and travels around on the primary side at approximately 250 cfm.

Jet/tune the crab accordingly and you’ll be fine.