318 with 675/318 or 974/360 heads Cam Recommendations

The KB167's are about the least costly game in town for decent compression ratio. Just one issue..... they are lighter than the stock pistons and will drop about 80 grams off of the stock bobweight..... too much change without a re-balance. Now .060" oversize ones will weight maybe 40 grams more, so that might be juuuust OK. It would be worth a call to KB to ask the actual weight of the KB167 in a .060" oversize. So there is that matter and possible added cost. If you get that actual .060" oversize weight, let us know; I can plug it into my spreadsheet and let you know how much the bobweight has changed.

360 heads are typically 71-73 cc chambers. 675 heads from the 318 will usually be 67-68 cc. Using the larger 360 chambers is like dropping the piston height about .030" and you'll drop a half a point of compression. With your altitude, you need all the compression you can get.

With the KB167's and nominal LA deck height, you get an 8.8 SCR with the 1008 head gaskets at .039" thick, and 91. SCR with the Mr Gasket 1121G head gaskets at .028" thick.

DCR will be decently good 7.5 to 7.7 with the 256 cam. You'll need it with your altitude. At 4000' elevation, it is like dropping 0.8 points of CR at sea level.