Having installed a new mainspring housing/magwell combo from Wilson Combat on a Dan Wesson Pointman, the trigger/hammer will function without depressing the grip safety? Seems there is not enough spring pressure on the grip safety? What's up?
A new MH shouldn't affect the GS. The last tang on the right of the leaf spring holds the GS out, maybe it is somehow compressed by the new MH. As you slide the new MH in watch to see if the leaf is compressed.
Another possibility could be that the new MSH is not allowing the GS to come back far enough (i.e., if the GS is not allowed to come back far enough, it will allow the hammer to fall, almost as though it is being depressed).
Try reinstalling your stock MSH. See how far back the GS sits. Then install your Wilson. I'd bet that the GS does not come back as far as it does with the stock MSH.
There are two "legs" at the top of the MSH. It may simply be that these need to be fitted in order for the GS to sit back far enough.
What Lemat said; I had the same exact thing happen to me with a Wilson and a S&A and all it required was some minor filing on the MSH tabs on top to allow the grip safety to extend back all the way...something that was tought to determine from visual troubelshootign alone.