Diy paint/high school budget
I sugeest you read the "sticky" under the body thread. all good info even if its not in your budget to do a "pro" type job. but understand these points:
you must have a good foundation! NO rust, NO flaking pant, NO comtaminants, as in oil, silicone, get an automotive cleaner as in the oil/grease remover from a REAL paint store, not Walmart of lowe's.
the surface must not be slick, needs to have have something to adhere to. one reason people prime with an epoxy primer, is it adheres SO well. and does good job as a sealer.
any dings, ANY imperfection you see before you paint, will be multiplied by 10 after you paint. just a fact. a flat will not show as bad as a gloss. ( one reason guys spray with "hotrod black)!
the "Rustoleum" oil based Tractor paint! ???? it is tough stuff, I use it on floor pans, BUT for one thing it is hard to sand off if you or another someone does a REAL paint job. it will not have a lasting shine in UV rays. I also, vote to go with PPG's second brand Omni or another co. 2nd line. DuPont, other companies.... I use Acrylic Urethane. nice shine, durable, cost effective, I don't care for the look of BC/CC... just me..
I would save enough $$ to scuff and clean off the metal, get a 2nd line of Epoxy primer, spray rattle can "guide coat" and block that and you will then see how many "boogers" will show up after final coat. or epoxy prime and come back with decent brand of " hotrod flat back'. the later would get you buy and NOT be a waste of time and $$.