http://www.rcuniverse.com/forum/m_8246301/tm.htm
check out this thread. there are lots of people in there with some real know how who can help you find what is right for you.
I have just completed building an RC10GT with a big block and I have clocked it at 62.5 MPH and I had limited space on uneven pavement I know with the right surface and space I will get it well into the 70's MPH