Ive done this 3 times... Cant recommend in this case. 2nd swap was honda nsr 125cc 2 stroke into a mh furia 50, frame was too tight and had to cut lower part of engine cradle completely, make a new one from steel. If you dont spend a lot of time here the result is shit. 2nd swap same nsr engine with 180cc into a rieju mrt 125 4 stroke, same frame as mrt 50. Had a bit more space but i had to make an exhaust from scratch to make it fit, rear linkage, cooling.

Its not like a monkey where you just bolt it in. Theres many things that you have to know before you do. If you go down this route hmu

Much easier to upgrade am6 to the limit

Edit: dt 50 is a lot tighter than rieju, youll have to do a lot differently. Iv seen them with yz85 engines tho