so i got some wood cut for a cabinet i was making. I was planning on making an 18watt marshall clone and so i cut the wood for a 1x12 combo that the chassis would sit in and had a friend finger joint it and i got all the materials to build this 18 watt amp i.e. tolex, grill cloth, piping etc. now after doing some more research and talking to people about the 18watters i dont know if thats the choice for me. i think i actually want the jcm800 2204 style instead. i love that gain sound it has and i think it would be a cool build. now my question is:

the jcm800 2204 is a 50watt amp. would it be a bad idea to try and put that in my existing cabinet(with a few mods of course) and just use a single speaker rated for at least 50watts? am i asking for trouble with that? i mean if i had to i could just build another combo but i really wanted to avoid that. any help would be great.