The classic way to make room for a HEI is a big hammer, and pound that area of the firewall back a little. I don't know of any way to move the engine forward in relation to the bellhousing without messing up the clutch-to-transmission relationship. I guess you could try to slot the mounting holes in the crossmember and move engine, transmission, and all forward about an inch, but that will mess up the position of the front motor mounts, driveshaft length, etc. It would also make the hole in the floorboard for the shifter out of place. I'd either go with a point-type distributor, or pound the firewall with a BFH!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!