whats a good set of heads

318 heads with KB167 pistons are probably the most cost effective choice for any motor producing up to about 320hp if you already have them.

If you want more power than that it may be a worth while idea to look out for some 360 heads and go with the KB399 pistons.

There is a massive 11.2cc difference between the KB167 and KB399 pistons.

With KB167 pistons you would have to mill 360 heads a massive 0.053" to get the same compression ratio as KB399's and unmilled heads.

0.060" is considered to be the limit for milling heads.

IMO If you were to compromise and build your motor to make about 350-360 hp you probably wouldn't have to do any substantial port work to 340/360 heads and could get away with a hydraulic flat tappet camshaft and it would last.

It would be more reliable, probably only cost about 2/3 as much and be a lot nicer to drive around town.