I doubt that would be available, but the general philosophy is that you’re best to take the junior equipment as a new hire. As a 756 FO you’d most likely spend your 2 year seat lock making reserve min pay at the base rate which is equal to narrow body rates. You’re much more likely to become a lineholder on the 737 in that same timeframe, have better scheduling flexibility, and make more money- and you have the ability to bid up at any time, so that option remains open.

Some will decide the more senior equipment suits their personal situation better, but for the majority, the NB makes more sense to begin with. Personally, I’d take out of base 737 & bid back into IAH at the first opportunity before taking IAH 756. YMMV.