There's a few posts around on fitting pressure guages, also opinions on whether they are of any use! From what I've read the presssure is quite low once the oil is warm, and there is little point knowing what the pressure is, when the oil is cold.
Just my 2 cents worth but if you fit a guage you will be introducing a new "point of failure" and I think oil pressure failure is probably what you are worried about, but the pumps are very reliable as far as I can tell, they spin relatively slowly, don't wear much, and it's pretty easy to tell if they are worn before fitting them. You might find yourself worrying about what's going on.....
I've not fitted a guage myself, someone who has will no doubt chime in and say how it's done, but in principle you need to measure the pressure after the pump and before the pressure release valve (PRV), a way of doing this is to drill a small hole in the crankcase into the right part of the PRV cavity, and then tap the first part of the hole so you can screw a small BSP or other fitting into the tapped hole, then use this fitting to connect up a pressure gauge. obviously there is a risk with drilling your case.....might be best to practice on an old case?
It's probably possible to make a PRV that is a PRV and also has a take off for a pressure gauge but I've not seen a post on that, there are also PRV with pop out buttons available to indicate the pressure is OK but I've heard these are more trouble than they are worth as leak, maybe you might use one until you get a new pump?
SRM pumps are quite pricy but as an alternative you can get hold of an A65 pump which like the SRM (also) has more capacity due to wider gears (tho I'm not sure if that actually extra capacity has any benefit as regards engine life and significantly higher oil pressure) and fit the A10 drive part to it (thats what I've got on my A10).
There are varying opinions on whether it is "worth" risking a rebuild for the sake of the price of a new pump but I bet there are alot more engines out there working just fine with old pumps than there are with SRM one's!