Adam,

Without being a speed freak myself, you can try an MVVS .49, or an Irvine .53.
An MVVS with the tuned silencer, could spin an 11.5x6 Bolly Clubman prop, at 13,600 RPM (5% nitro), which is more than enough to yank your model off the ground. Most muffler equipped .60s do not have such power, spinning an 11x7 (equal load) at 13,000 or less.

The Irvine with a Genesis tuned silencer will probably be close.

An engine of the .40-.53 size will most likely be much lighter than a .60, so no tail weight is needed.

[link=http://www.justengines.unseen.org/]Just Engines[/link] has both engines. The MVVS has an optional rear mounted needle, if you are so keen on using one.