Ben:
A common scenario is using the 410 or 428 crank (3.98") to yield 410 cid. Remember you have an externally balanced crank now, so you will need the flywheel and balancer. Obviously, this is the inexpensive method
A 406 has a 4.13 bore (390 is 4.05).
Another option is
Flatlander Racing. These are 416 and 430 stroker kits for the 390. The price is listed about $2000 for the 430 setup. Don't know anyone that has one.
BTW, pentroofs rule.