340/904-999 combo

In my shed I have a 340 for my Valiant; '69 vintage, Edelbrock Performer RPM intake, a 800 CFM Thermo Quad, headers and a '68-spec cam kit. The rear is an 8 3/4 with a 3.55 cone sure-grip and I am going to run body-color cop wheels with 225/60/15 tires. My tranny selection is either a 727 or a 904 w/the beefier 999 guts in it. The 904 and 999 I have, got 'em for free. I know they can't take the power levels that a 727 can, but I am not planning to go crazy with the 340 power levels. Nor am I setting my sights on 11-sec 1320' trips. Anybody ever build this tranny with this combo? Suggestions or tips? I am after building a respectable, well-rounded street performer on a budget (and I've done REALLY well so far with the help of friends on the parts and labor- I don't even have $800 into the whole thing and the car is an 87K mile survivor Grannymobile). When I get more serious I will build a BB stroker and a better trans, but for now the free price and the lower drag of the 904 make it tough to beat!