I have a stock 400 block I have installed a performer kit from Eldelbrock Cam,intake, and 750 cfm carb. Need to now correct temp plugs I should install.

 

Generally, the best advice is empirical - try a set and see what happens. Start with middle range plugs and run 'em for a week or so. Carefully remove a pair (one far from the carb, one close) and check the condition. They'll tell you the story. Nobody, but nobody can predict the EXACT correct plug beforehand.