sbc mounting location on frame rails

[jrusher]

Hey guys im trying to find out which location on the frame rails is the proper spot for a sbc 350 or 283 1965 c10 column shift auto truck ? From most pics that ive saw it looks to be the rearward holes on frame rail?
Ive just swapped in a built up 350 i had laying around in my shop from my chevelle into my truck and the old 350 that was in there was mounted in the rear holes on frame rail but the hei distributer is very close to firewall. It also has a t350 tranny which the cross member looks factory but not totally sure. It still has some clearance at distributer and i can adjust it but was thinking of moving engine ahead to the front holes for more clearance and take up some of the space in front of radiator as there is alot of room.
Not sure if its worth it getting a new driveshaft made up but be nice to get rid of the two piece shaft and steady bearing
What have most of you guys done when swapping in a sbc ? Thx in advance