No question that it's possible!!!!
The only catch seems to be fitting a 2 speed, which these cars need to be competitive in a normal racing enviornment..... BUT, if NO ONE has a 2 speed, who cares???
My OPINION is that probably the Losi lends it's self to this type of conversion based on the fact that they have some components for the L8ight model that will work well for this application - short shock towers, short shocks, front and rear body mounting systems. AND, truggy chassis=GT2 length and body application, buggy chassis=GT1 and body applications. From what I have read on some of the dirt oval forums, the body mounts will adapt rather easily to other chassis with some creativity. PLUS, there are some really good deals out there on the L8ight model!
This certainly could be a fun class running ALL of the vehicles with single speed transmissions and conversion chassis. BUT, the 1st person that gets a 2 speed will clearly show WHY the 2 speeds are used!
Is this cost effective??? Probably NOT as much as you would think since quite a few parts need to be ordered AND the bodies are VERY expensive unless you go GT1 and use the ProLine/Protoform body..... Have you priced GT2 and GT1 cars both new (every now and then you'll see a new GT1 car on Ebay and around the .net) and used??? They're NOT very expensive compared to some other scales and styles of onroad car - and that's why their popularity is growing!
Here is a link to the Heart of America rules on IGT, as you state, not a bunch of application as far as you guys are concerned since you want to get a group together and race amongst your selves BUT it does outline the throughts on the class and a group of engines that are close in output.
Good luck and let us know HOW this turns out!!!!!!