Hiya Cavalo,
The original foot length for the standard W32 cutter rig was to be 15'10"...yeah, one BIG foot! The word in the wind about weather helm is somewhat true; the boats can develop weather helm, but that is not necessarily a function of their foot length. It's a number of things. The short answer to your question is that it is held by Kern Ferguson, a gent with great knowledge on the Westsail sailplans, that the W32's main should be about 14'10" at the foot for "overall balance." He also suggests full battens and a full roach, which Dave King and a few others have said really helps the boat's performance. When we replace our main, I'll probably go that route, too.
That said, I have a 15'10" footed, battenless, roachless main and my boat hasn't show much of a weather helm issue; at least nothing out of the norm for a full keel boat. I believe most of our issues can be dealt with with proper luff and foot tensions for given wind conditions; draft control is essential! Also, on all sailboats, people tend to oversheet for fear of seeing anything but a "tight" sail. Mainsails, when going upwind, should always show a smidgen of true "luffing", that is, puckering or bubbling in at and about a foot or two abaft the luff, depending on the depth of draft. There is a giant aluminum pole in the way of the immediate luff catching wind, so it is proper that the luff will not be "tight".
Ease the sheet, keep the draft flat and well forward when the wind pipes up, and you probably won't have issues with weather helm unless the sail is badly worn (and, in your case, with a torn sail, you're guaranteed not to have any!) Also, people commonly thing that going vangless and letting the sail "breath", aka letting the boom lift to spill wind, is a good idea. This really does little but hurt your sail. Keep your sail properly shaped with a vang on all points of sail and you'll be able to control your weather helm. Don't forget good luff tension on your headsails to keep your healing moment down, too!
Also, of course, reef down. We go to the first reef in the main at ~15kts, 2nd at 22-25kts. This keeps weather helm in check.
~Aaron N.