Punctuation would really help your post out. I am having trouble udnerstanding exactly what you are asking.
First of all, the C4-2.3 was a very rare combination. The only bellhousings available are from the mid 70's pinto. Unless you already came up with one of these, none of your other questions even matter.
For the flexplate and converter, you can use pinto parts. There are still stock style converters and flexplates available from auto parts stores for the pinto models that came with the C4.
As for you C5 commend, I am completly lost. There never was a 2.3-C5 combination... Besides, the C5 is just a C4 with a lock up torque converter. To get a lock up torque converter, you would definatly have to have something custom made if it is even possible.