More generally I advise you to read the following posts by George P:
https://pantera.infopop.cc/top...d-performance-tuning
https://pantera.infopop.cc/top...d-performance-tuning
https://pantera.infopop.cc/top...mber-4v-heads-q-code
https://pantera.infopop.cc/top...00-bhp-351-cleveland
https://pantera.infopop.cc/top...using-all-ford-parts
https://pantera.infopop.cc/topic/351C-super-stock
and there are others, it is an incredible wealth of knowledge of the 351 C.