I wouldn't worry about port and polish if you're going to turbo. Is there power to be made if you do? Of course it'll have a LITTLE more power, but the cost isn't worth the benefit as the RC51 heads flow fantastic in the first place (Plus I doubt the difference in spool will be notable if you properly size the turbo). Same thing goes with increasing your cylinder size, it will yield you a little more power and a little better spool but not enough to where I'd go out of the way to do it. I've already turboed plenty of applications and the good setups are always the simple ones.
I'm going to have to ask if you can provide a little more info on this.
what more info do you need?? i think thats all you need to know, especially when thinking of your previusly posts, i think thatīs all the info i want to share with you, i just wanted to point out that a big bore is possible