T34 is the perfect road engine, end of. Unless your flying up motor ways then there isn't a lot that will catch you for nipping about. Is stay with it. You've a nice ported head. With a decent inlet cam you could make a sweet 400/400 engine. None of this ab07 shite though you want something reasonable hot on the inlet and timing key,

Best advise though, ring Karl and talk to him as all tuners have different ideas

Your head would take a t38 though but you loose a lot of bottomend, and would only be catching a t34 engine from 4th onwards

Again depends what you want from the car and its main use chop

Jim