"If a little is good... a lot has got to be better!"
LOL, one of my favorite sarcastic lines. Used like when it comes to glue and bondo but applies for displacement also. Now do you mean actually dropping a dime into the juke box, jumping on your bike and flyin hell bent to another Cafe' and back before the 45 is over? Or what is commonly used today with a custom parts list a mile long available to make it easy?
Honestly, you will get a wide variety of oppinions. Personally, I want a 500 single next, built reminisant of the BSA Gold Star or Norton Manx. Verticle twins in the 500-650 range were the common ones back in the day, but then you got the 750 Nortons...Now days 350 twins are favored. They were light, compact, easy to toss around and common... parts galor