C4 Help?

Ok so here goes my story, So I took down my C3 today to install my C4. To bring it down trying to figure out how to drop it with out taking down the exhaust pipes. So finanlly down when I am bring my C4 to bolt up I am not able too because the torque converter does not bolt up to the flywheel. The torque converter that came with my C4 is to big for the flywheel. so there is no why i can bolt up my new tranny. What or where do I get the correct torque converter for it.
Also how do I convert the shift. Here is my Serial Number from the new Tranny: C6AP-7DO27-C.

Thank You.

 

You can install the C3 input shaft and converter in your C4

 

You need to get the correct flex plate. They came in 157 teeth and 164 teeth. Also 28 oz (early)and 50 oz balance (post '82 IIRC). There are 2 different torque converter bolt patterns as well ,(10 1/2" and 11 7/16").