I wouldn't bet much unless your 100% sure what he has. $100 isn't much if you do lose. It's worth the risk I would race him but obviously be safe about it.
I hope he's not trying to pull a fast one but I might try as long as I can pop the hood to both cars I'm fine with it and I would take it on the long abandon road around here just to make sure it safe for as safe as racing can get for us lol