I have used a few in 1/72 scale.
It seems that anything goes. Some are great, and some have been a real struggle.
I have had to drill out the engines for the prop shafts. As far as fitting under the cowl, it has depended on the kit. Some fit well, some required extensive work.
If you are a novice I'd pass unless you are ready to POSSIBLY put up a fight. The good news is they are inexpensive and if they look like a hassle shelve them for a different kit.
Sorry I couldn't be more specific.