Welcome to Shipbucket!
I'm sadly not up to scratch on the FD planes, but the kitbash looks well executed. The plane itself, now...
Not to complain, but the proportions make the front part look much smaller than the rest. Maybe it's only the Mig-23's fat rear end showing up, maybe the fuselage is longer due to the meshing of both aircraft.
As pegasus206 mentioned, there is some work left on the intake area, which could also allow you to move the nose section back and shorten the whole fuselage.
I see what you mean, I'll try my best to make a revision as soon as possible.
(P.S: I'm not too sure what the deal is with the proportions, I'll take a look at the reference information. My mistake.)
Thanks for the constructive criticism!