I don't know anything about Quasars but I think that you could
work it out with a good
sailmaker.
Back when Quasars were first designed they probably had symmetricals. I love symmetricals but they have different needs from assys. If you are going to put an assy on the Quasar I would recommend a prodder (to get the assy away from the seagull striker). This is going to change the assy dimensions.
I am a big fan of a Code 0 but the huge genoas of the Quasars would probably make this a little redundant. So an assy could be a good fit. If I get another assy, I would like to get one that could roll its luff in withouth collapsing. I see lots of
race monos doing this - Transats and TP52s, just sailing along with the vee on the luff rolling in. That would be gold for a cruising
boat.
Then I would still recommend a symmetrical for square running. Although the Quasars are not too beamy so you would have to keep the foot length down.
cheers
Phil