It's upside down dude!
The drilled starter bolts are Small block Ford or perhaps earlier Y-block.
They are normally 6 big 7/16" UNC treads, two 1/2" dowels in the top 180 degrees of the circle, then some smaller bolts for the backing plate. It has a two bolt V8 starter.
A simple check is to measure the centre to centre bolts.
1.Measure the top. Should be 5 1/8"
2.Measure the two widest dowel holes. These are the plain ones, without any threads (Dowel Pin to Dowel Pin) should be 14-15/16"
This web address list all of them for C4 and C5 autos. Since manual gearboxes go on the same block, 3 and 4 speed V8 engins are the same.
A 250 or 300 I6 is just the same as the Small Block Ford, although some starters motors vary from 3 to 2 bolt, 157 to 164 teeth, or some odd ball 153 teeth numbers for the older Y-blocks.
Summary
The pitch centre diameter of the six 3/4 inch head bolts on the back of the bellhousing is generally 8.25 inches from the centre of the crankshaft, but some are smaller, equal or bigger than this dimension. The bolts are arranged (clockwise from left as viewed by driver )
1 273 degrees clockwise from vertical, 8 1/4 " outwards
2 299 degrees clockwise from vertical, 7 7/8 " outwards
3 343 degrees clockwise from vertical, 8 3/4 " outwards
4 17 degrees clockwise from vertical, 8 3/4 " outwards
5 57 degrees clockwise from vertical, 7 7/8 " outwards
6 81 degrees clockwise from vertical, 7 7/8 " outwards
S2, the Starter is indexed at 106 degrees, and the driving gear is about 8" outwards
D1 Dowel one is at 290 degrees clockwise from vertical, 8 1/4 " outwards
D2 Dowel two is at 68 degrees clockwise from vertical, 7 3/4 " outwards
See this BIG PICTURE of an FMX auto from a SBF for more details:
http://www.hpphoto.com/servlet/LinkPhoto?GUID=41ff2225-7a4a-41a9-11b3-7fa265724979&size=
You may have what you need right there!
Check this for more data
http://mmerlinn.tripod.com/trans/fdc4f/fd9c4bhd.htm