How badly destroyed is the replacement engine you bought? From the sound of it you could take the 2 and built yourself 1 good engine. A gasket set and maybe a set of rings and you could be up and running in no time. Just get yourself a proper manual and take your time. 185/200 engines are pretty easy to rebuild.
1979 ATC110
1983 ATC110
1984 ATC110
1984 ATC125M
1985 ATC110 2 of them
1985 ATC110 The wife's
1987 ATC125M
1985 ATC250ES
1984 DX225 with 250 timberwolf engine and swingarm. Wolf in DX clothing