You’ve asked a couple loaded questions!
Let’s start with vintage vs. Modern. First of all, this depends on what your definition of vintage is. I’ve been in and out of the sport for about 15 years now and on the chassis itself therw hasn’t necessarily been much change. I currently have a CRG Road Rebel. The fram is VERY similar today as what it was fifteen years ago.
The biggest difference is the accessories, for lack of a better term. Fifteen years ago almost everyone was running the same type of brake system, bodywork and 40mm axels.
2001ish started the movement to 50mm axels. New regulations out of Europe meant new crash tested body work and most of the manufacturers went their own way with braking systems.
next thing was going from 17mm to 25mm spindles and wider front ends. In the last five years or so there has been a movement to softer chassis, and a lot more 30mm frame rails… as opposed to 32mm.
In all honesty those are the major changes in karts in the last little while. I’d recommend getting something relatively modern. As for chassis, It honestly doesn’t really matter, it is more about support. If you’re just going to be driving and practicing as opposed to racing I’d buy something that is supported by a kart shop that is convenient to you and seems to have reasonable prices. If you’re going to race, look at who is out on race weekends. Remember that you will spend A LOT more racing than just practicing.
TonyKart has tended to produce a chassis that goes soft in recent years, but if you’re not racing that last .15 doesn’t really matter. All the karts are designed to work properly when being driven to the limit, so don’t assume that one is necessarily will be better for a noob, or easier to drive.
I can’t really comment on engines, because I don’t know if you’re looking for track time or to go racing. If its seat time you want, anything can be run rich and relatively cheaply. I’ve run an ica for the last while, which is probably the most expensive thing to race ever, but I run it rich and only rev it to 17k instead of over 20.
if youre racing look at what people have, and what classes are popular.
Talk to local racers!
I hope this helps you in the right direction and will suggest you check out the general discussion forms for similar topics, and it tends to br visited more.
The other thing I will add is that personally I’ll only ever have a kart with self adjusting brakes. Shimming brakes is the biggest pia job imho