OldScaleGuy,
Pay special attention to proper baffling of the cowl, or you could end up like me, seizing up your new Twin. Now I have baffles build from 1/16 balsa and then glassed over for strength. Those baffles force the air flow directly over the fins and then down out the bottom exit. Make sure the air after going around the fins will be directed out without being disturbed. In my case I had a good air intake but my exit was somewhat blocked and the cooling air was trapped, causing overheating. A good insurance to prevent seizure is for the first time to fly for only five minutes maximum, land and check the temperature with a infra red gauge thru the front intakes. Any reading over 250° F should be considered hot.