Methanol will like the compression. The nitro will NOT like it. Running some toluene in your fuel will help the nitro be more tolerant of the compression. A quart of toluene in a 5 gallon jug of mixed fuel will be a big help.
I would plan on a strategy that will get you an easily adjustable compression ratio. Get pistons that will deliver 15:1 with the thinnest head gasket you can possibly run. Then figure the thickest gasket you could run. For good "squish" in the chamber, I'd not go thicker than .060". Thicker than that can actually promote detonation. Hopefully, you can shed a full point of compression this way.
Another relatively cheap/easy way to lower compression is to grind the valves. A brand new set of valves can have a HUGE margin on them. An old set of valves can be ground down to nothing on the margin and that will really sink the valve in the head a bunch lowering your compression significantly. Valves are probably cheaper than pistons and could be swapped out quickly during a head gasket change.
So, a gasket and valve change and you might drop a couple of points and that's going to be plenty good enough for 30%. 13-14:1 will be fine using toluene as a stabilizer.
Another thing to consider is the cam. If you're running a short duration, short overlap "stump puller" type cam, the nitro will tear things up. It will hate it. Your "dynamic" compression ratio will be very high. A long duration cam, with tons of overlap will lower that for you and the high static compression ratio won't be such an issue.
Spud
