I would try a standard format to bid from. For instance, i have a one page questionaire as to everything i can think of in a single fam home, given accurate info i can give accurate pricing. Bids are done sq.ft, $ per stop, $ per service amperage, etc....whatever works for you , and is in the 'ballpark' with other sparky's in your area. I would take the time to seek out your competition here, as it behooves you and they to be similarly $$$'ed.
Save the T&M for the ones who don't know what they want ( weed them out too, as they are a pain..)
Anyone here will tell you there is no glory in T&M, the pot of gold is in concise bidding. This solid pricing should appeal to a GC who is universally the 'liasion' bettweeen you and the customer. The customer knows what they are paying for,the GC knows what his cut is, you know what your payment schedule is.
One thing i can tell you is that GC's always love the new kid on the block, beware