you could do all the porting you want to any one of these jugs, and it will still go slower than the stock jug if your jetting is way off, your timing is off, your exhaust is clogged, etc. Portmap is not HP.
That being said, with a little dremel work, all of these cylinders could go faster than these portmaps allow, if all other tuning is correct. If you want to port a jug, look at JAPP's puch calculator on the wiki and read the articles on calculating port timing.
Sorry to hijack your thread...