The conversion to a lithium battery is not difficult. And, as @PatR points out, lithium ion is a better choice than a Lipo.I would suggest going with a LiPo version if you can find it at a good price, since the 8-AA battery version burns through batteries rather quickly. I only get about about 10 - 15 minutes (depending on use) out of a set of AA batteries.
Ask the seller to take a picture of the slide mount. If it has the 3 contacts on the slide it will work.but perhaps there were multiple LiPo versions with silver bases.