yeah a shock is not designed to carry any of a vehicle weight what so ever. it is only there to control your suspension bounce. the weight is carried in the springs
some people run an air shock on trucks and its still not a good practice but with a real frame there is normally no real damage.
my floor pan failed on the left hand side, and with those big meats out back if it fails your gonna tear up the tires and the quarters panels some due to physical contact. just count your blessing it hasnt happened.
what kinda of rims are you looking for??
Glen(soaring) has complied a great FAQ section http://www.mustangv8.com/forum/classic-mustang-technical-forum/classic-mustang-faq/
there is a wheel and tire fitment guide in there iirc its located at www.dodgestang.com
iirc(if i recall correctly) so about the internet jargon, if we uses anything abbreviation that you dont know, dont hesitate to ask what it means(i learn new ones every day