If you want to use the original trans you will have to use a early 65 on back 289 as the bellhousings will bolt to the original trans. Mid 65 and up the small block fords have a 6 bolt bellhousings and the mid 65 on back had a 5 bolt,49-64 trans had the bolt pattern where the bolts are colser to the trans case where the later had the bolts farther from the case,I am not certain when the trans bolt pattern was changed as I am quessing it was changed when the went from 5 to 6 bolts. You could also look into a racing bellhousing as they might have both trans bolt patterns. If you need motor mounts a local rod shop sell mount kits that use both the front sump pan and the later rear sump. Jeff