Hi Bob, an welcome to turning and the forum, I'm with Dr4g and Brian on this one, 1st in what way do you want to go with your turning, bowls, hollowform or spindle work, all of it, along those lines Brian is right in you should start with one of the lathes you have, should both be working, you've not said nor as to what models you have, short bed, long or bowl lathes.. get started, learn as to what you'd like to do, (pens can be turner on a large lathe just as well, but larger forms can't be as well on a small lathe) then you'll find out as to if you'll still want to carry on with it, that love it kind ...
.. then chose as to which to do, re-build, sell both and buy new, as has been said a well setup Graduate can't be beat, you'll spend alot more on something new to get something as nice. It's working out what you want to do and if you'll stick with turning in the end, with the Graduate you've a far better chance than on a lesser lathe, where most have found turning to be difficult or have other problems, as in another post, as too the Record tool post ..
Wish you well with what you do in the end, what ever it is enjoy, it should be fun, take care and be safe at all times.
David