Bigger Valves in AFR 165's?

I currently have a pair of AFR 165s, I plan on removing them for a port and polish. I was wondering how much work it would be to upgrade to 2.02 valves. I know the valve seets will have to be changed, but can a machine shop just inlarge the current sive and install new valve seets? How expensive is it, any guesses?

I don't wanna put much more $ into this motor! I almost have everything for my 383 windsor. I got victor jr heads, forged 3.750 crank,forged pistons. I just wanna lil more power from this 306 intil I can afford the turbo and igniction! Do u guys think the 351 Sportsman would be worth the 1,700$ or would my stock 71 model block be enough?