Are you replacing the OEM OP gauge because yours is broken, or is there another reason? From clarks-garage.com, the resistance from the OEM OP sender on an early motor at various pressures is as follows - you could probably use this info to look online (or email vendors) for a gauge that matches:
Oil Pressure (Bar) / Resistance (Ohms)
0 / 10.0
3 / 116.0
5 / 184.0
Rather than replace just the OP gauge with one that's compatible with the stock sender, though, it might be worth replacing the sender as well and go with a fully new setup of sender/wiring/gauge. That would also be a good opportunity to put a T-connection on the OP port for an electric OP dummy light, as well. This would also give you a little bit of sensor/gauge redundancy in case one of the sensors goes bad.
For oil temp, I'll just echo what's already been said - with an early oil pan, drilling out the drain plug is your best bet.