My reccomendation...Tri-Y's if you are willing to change to late 65/66 motor mounts.
Otherwise...take advice from those more knowledgable...check how long they have been a member, how many posts and what their car and mods are...
Headers are a somewhat personal preferance.
Long tubed DO hang low...but they can & do provide some benefits.
If I had mine to do again I would either use hipo manifolds or the tri-y's again.
Verify which motor mount you have...check any of the major parts sites for pics...if you have the late 65 - 66 go with the tri-y's.
again my .02