Propane conversion

["Joseph M. Shaw, II" <MikeIIDC@domain.elided>]

Hi, All!
You will probably all think I am absolutely crazy for this, as I have so
much trouble with my Damn Scout (a term of affection, I assure you)that
I should never dream of taking on anything else.  Regardless, I have
come across what is apparently a very nice mid 70's crew cab pick-up
that I may be able to pick up fairly inexpensively.  It's body is in
very good condition, original paint, no rust that I could see, and it's
been inside a garage for a few years not running.  It has a propane
set-up on it, though, and I have a few questions.
1.)  Should it run on regular gas as well as propane.  I thought it
would work on both, but the gentleman that owns the garage where it is
said that he thought it had to be converted, but that it was simple to
do.  When I went back to him a second time, he said it would run off of
both.  I had tried to tell him this the first time, but he was adamant
that it wouldn't.  I thought that since I had said so, it may have
convinced him, and he probably just didn't know the difference.  I had a
friend in New Mexico that had a F**d with a propane kit that would work
off of either.
2.)  If there is a conversion that needs to be done, is it
difficult/expensive?  Has anyone done this?  Any tips?
3.)  I know that converting the older style (69 and earlier) body style
models from two to four whell drive was supposed to be pretty basic. 
Are these later models as simple. or did they change anything?
4.)  And if you think you may want this truck, let me know.  I don't
know what they really want for it; they've simply asked me to make an
offer.  I am not in a position to give much for it, but they obviously
don't want/appreciate it, so I'm hoping to score it cheap.  I'll let you
know, and if I don't go for it, I'll post what kind of price they're
looking to get for it.
Thanks for any advice.
Michael