Unfortunately it is not as simple as that. The 5 bolt bellhousing used a "narrow" case T10 and when Ford went to the 6 bolt bellhousing they switched to a "wide" case--which means they extended the mounting ears. Due to the need to continue warranty the older narrow transmission, they also included the narrow pattern on new cases.
Unless your T10 was replaced in the past by a wide case with the dual pattern, your going to be in a tough spot.
Although the cases pictured below are from toploaders, the T10's would have went through the same changes:
There may have been a few bellhousings that had both patterns (?) but they would be quite rare being only produced for a year or so around 1965--but not all 65' bells would have been cast this way.
Your best bet might to be to find a used Lakewood 15200 (or other brand) SBF scattershield since came with the dual pattern for both transmisson cases. They still make them that way today. Ebay would be a source for used, but be sure it comes with the blocking plate:
A blocking plate looks similar to this generic one I found:
New scattershields (Lakewood 15200) come with them. Used scattershields often come without as the owner discards this needed item.