I run one of these (best price I could find). It's 1/2" phenolic material. I had to open the holes a bit for the 825CFM demon carb I run, but it should work fine on your carb.

I bought it specifically to block heat from getting to the carb, and it definitely helps with that. It also made my engine run better, so that I could close the butterflies at idle from where I had with no spacer, which made it run on the idle circuit more and it was easier to tune. Seems to have more torque now too. Probably the best $13 I've spent.

http://www.ebay.com/itm/130709764613?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649