1/8 Buggy Advice Needed

I am pretty new to this stuff, so please be gentle. So I have decided that I want to convert a 1/8 buggy. I have narrowed my buggy down to either an rc8 or 8ight mainly based on ease of finding replacement parts. I would like some advice from the Jedi Brushless Conversion guys on the forum. I don't really have a tight budget, so I am more concerned about reliability and performance as opposed to cost.

Use: Mostly running at a track during practice and maybe a few a races, but nothing serious. I also want to be able to do some insane speed runs on the street occassionally. I have a FLM Rusty VXL with 3s 8000 Lipos that I love to blaze up and down the street at 65 mph+, so I am looking for similar street power.

Motor: From the research I have been doing, it seems folks recommend the 1512 or the 1515 neu motors as the gold standard. I was leaning towards the 1515 because I may do a Truggy after the buggy is done and might want to swap the motor. Beyond that, I don't know which version is better. The 1, 1.5, 2.5 or y and d winds, etc.

ESC: it seems the quark monster pro and the MGMs are highly recommended. Is one better than the other? Does one have a significant weakness?

Batteries: It seems people run 4s on the track most often, but since I want to go fast in a straight line too I need capability to run 5s and 6s? Is there a recommended MAH? By the way, I am looking to outright destroy nitros on the straights, but still have a car that is manageable on a track My Rusty can barely make it around a track, but puts pretty much any nitro to shame on straights when I have the 3s in it. Too much power for turns. The car just breaks loose and donuts.

Car: Which is the better car for a conversion? Again, I am not an experienced racer, so I probably can't pick up the small nuances between the cars.

I appreciate the feedback.