Mario;

The Europeans have been posting (and raving) about a dry-ice blasting method in the last couple of years...sounds good to me...if you can find it reasonably in your area (or even on this side of the slightly less environmentally conscious Atlantic)...cooling it will make it less pliable...freezing will make it hard and brittle even, and able to be removed in slabs...or, can you just do small repair areas and wait until January for the major work?

Doing it with a solvent will be about the messiest job I could think of...just about any solvent will work, but must be covered and kept from evaporating while its doing its thing...so unless you have the car on a rotissary and upsidedown to prevent the stuff from running away...use a jell type paint stripper (I presume that's the consitency of the Eastwood stuff, if not I'd use Zip Strip or similar gel type) and here's the Hot Tip: After applying, cover with wax paper or plastic to prevent drying and DON'T RUSH IT...remember, it's got to get through about a 1/4" of vintage tar!!!

Cheers