To be honest, either of those types of bombs would do. The earlier type, as shown in the Stirling pic, couild go in the wing cells, as they wont be as visible. The 1,000lb bombs were more of a tactical load, against military targets such as the V1 sites for example. Main loads were incendiary and 500 pounders a lot of the time, especially against cities and large industrial complexes. The incendiaries started the fires, and the blast of the bombs not only caused destruction (mainly disruption too, due to time-delay fusing), but spread the fires.
I should have some pics of the various bomb types and capacities, alongside each other. I'll try to post them in the next couple of days. I want to try to finish my Lanc first, so that I have time free to catch up with all the scanning, CD making etc to send off to various people. I think my local Post Office must think I'm running a world wide video or porn service or something, the amount of packages I take for different countries!!
EDIT:- Forgot to mention - yes, the wing bays were individual cells, with the bulkhead between front and rear.