You write 'critical monitoring'. And you want to kludge something together ? 
First rule of engineering : if it works , leave it alone.
I'm not sure if you're being factitious, but I am not trying to kludge anything together, nor am I planning to mess around with anything that's working fine.
I am trying to assemble a working spare, ready to be used when called upon. That is good engineering practice, is it not?
Yes, it is working, but if it dies it will very suddenly be my fault.
I am just a lowly electronics technician, on a drilling rig in the middle of the sea, working for a company with an incredibly slow moving buerocratic stores/management/logistics/purchasing circus. I can't just get stuff on next day delivery from the online retailer of my choice, nor nip to the local computer shop.
Ah maybe you're right, fuck 'em, who do I think I am anyway?! I clearly don't know what I'm doing. Thanks for keeping me right, Sir. At least a drew a cock on a 690v busbar today.