Need some advice?

I have what most would call a rustang, and on its way to its new life i have two questions. First, i have put my engine back in but I am having trouble getting the driver side bolt for the motor mount to go all the way threw? Anyone have any tricks of the trade they could share with me. I have never had this much problem with a motor mount before. Second to give the rustang a makeover to her new beautiful self, I need to do some major metal work, part of it will include soem pathc work on the steel, but I am not sure what gauge steel the original metal is? I do not have any micrometers to measure it myself so I thought I would ask the rest of the mustang world. I appreciate all the advice. I live in Hawaii, so buying new sheetmetal will have to wait til I get back mainland side.

Miles
 
I've heard of fitment problems with new motor mounts. Some guys test fit them to the motor and brackets before trying to install the motor.
A good source for "patch" metal is an old fender/door/hood that you're not going to use and that's got a good area to cut from.
 
Original sheetmetal for the early mustangs was I believe 18 gauge. Replacement panels and patching sheet metal is about 19 gauge. A little thinner and a little harder to weld but easier to work if you have to shape it. C6AE is right, the best patches come frome old sheet metal.