Porting the heads is probably worth 3 tenths, converter would be another few tenths, steeper gears a few more....basically, between porting the heads, steeper gears and a converter swap, you should be able to get in the high 10.9's.
X2 that's what I would do....... Would have from the start. My brothers 408 in a 70 challenger best to date 10.7's with a solid cam and 1.5 rockers 850 double pump.
