EDIT 1/15/23 : The difference between v1 and v2 is....
v2 has a much nicer looking engine in comparison to v1 and In order to make it fit into the cowl properly I had to enlarge the inner ring. The size of the cowl hasn't changed other than that so it still fits on to the fuselage as it should.

I re-sampled the original cowl so it would match and fit the original on the E-Flite 1.5m Texan. I added a support ring so the radial engine will fit nicely and allow you to glue it in place. In comparison to the original it adds very little extra weight. Print your cowl in white and the engine in black. Paint both as desired. The picture is added as a reference only. Print your parts separately. There are no screw holes in either. That's for you to work out or as in the case of a buddy he used magnets to secure it to the fuse.
My apologies for not being able to link to the original motor which I have reworked as well. I found that when I first started and didn't know about tracking a file here. Kudos to the maker though.

EDIT: I designed an exhaust pipe for the plane. You can find it here...
https://www.thingiverse.com/thing:5318033

Prusa

I3 MK3S

No

Yes

15 or 20

I used supports touching build plate only.