I always build it the way I want, then heat the hammer to bend it in place. Sometime I need to bend the nose of the hammer, and then bend the spur, indepenently.
With most locks, the bolster is too thin, and if you line up the hammer without widening that bolster, you get some lock panels that are too narrow (in my opinion). This plays havoc with the forearm width. I usually solder on a shim to the lock bolster, to throw the lock out further, especially if the lock panels are tapered wider at the front.
You can't fudge much with the back/forward placement of the lock though. If you are off in that direction, you can bend the hammer, but the recess may not strike the nipple squarely. I did that once by accident. The hammer lined up with the nipple just fine (or so I thought), but when I placed a cap on for test firing, the hammer hit the edge of the cap, and stopped right there. Wouldn't even fire. Back to the shop.
It's a tricky area. Bill