Hey Hawken,
Lock panels are a tough one to envision without handling some original guns (or some very well made contemporary guns). There are a few small tricks to ensuring slim lock panels and an appropriately sized stock. Some are easier to do than others, but I'm just going to go down a list:
Precarved stocks - not all precarves are made equal: It looks like the lock is positioned correctly on the barrel flat, but you still have loads of wood underneath it. This either means the web between the RR and barrel is very thick, or that you have lots of wood between the triggerguard and the ramrod. Before inletting the TG, I'll drill a 1/16" hole into the RR channel where I know the forward extension of the guard will cover, and I measure the thickness. Figure out how much you're going to inlet the triggerguard, then add a small bit. It varies by gun, but I like to have no more than 5/32 web at the breech, and about 1/8-5/32" thickness between the ramrod hole and the bottom of the stock. My guess is the stock you have has much heavier sections in these locations.
Pin the triggerguard tab from inside your lock mortise. This cleans up the exterior look and allows you to slim away without interfering with the pin hole (and unless your TG has an incredibly short tab, it also is a good mental reminder of how much wood needs to be removed from the stock)
Keep the wood adjacent to your tang and triggerguard perfectly flat, then add carving and details. See photo below. Do this on the lock side and repeat on the side panel as well - bring it right down to about 1/16-1/8" from the top edge of your sideplate.
Lastly - with most precarved stocks, try to consider the lines and moldings as "guidelines" more than actual rules - just about every precarved stock I've handled has required much wood removal around the lock panels and especially forestock.
Go out and have fun shooting the thing, then build another
This image below isn't of any specific rifle, but gives you an idea of what I'm talking about for shaping.