Let me start off with a "Hello,
My name is Nicholas, and I have a problem"
Don't know much of what I am doing, total noob, and could honestly use some advice on the subject.

I recently made the purchase of a somewhat beat up mid 80's Miyata road bike for not too much.
I had the full intentions of bringing her back to life... however, seeing as I have never done this before, I have run into a snag here and there.
I did my best to take mental snapshots (real snapshots would have worked significantly better... but whatev') of everythings placement and location, as I removed the hardware to paint the frame of the bike.
I painted it a beautiful powder blue. Simply stunning it is.
But... I've kind of screwed up.
I reinstalled the brakes/lines, drivetrain, handlebars and such components, wheels etc... no sweat.
No idea how to reinstall the derailleurs.
I think to myself in ambition... "So what! I wanted a single speed anyway!"
But of course, with no derailleurs, the chain is not in good alignment with the chainrings, and flops off after several revolutions. (Although the tension seems superb)

SO! Enough with the chit chat and on the the Q's!
Will this require a new cassette with spacers??
Or will I just need to bite the bullet, and learn how to re-install the derailleurs?
OOOooorr is there some option that my un-educated self has not yet been capable of considering?

Any help is immensely appreciated, and hopefully the more I do this, the less frustrating it will be.
By the way, I nearly died reinstalling the chain with the chain breaker. F'ing balls. I've never been so profane.