Metrastar
I have had several of these meters, and found that they were very accurate meters that gave almost perfect results over a wide light range. They are based on a CdS photo cell, a PX13, 1.35 VDC mercury battery being the power source. The PX625A a 1.5 V alkaline being the closest commonly available replacement, although Wein marketed a zinc-air cell that comes closer to being the correct voltage. There are several adjustable resistors built in for calibration, and it may be that the slight error of the 625A could be compensated using them. I guess a ASA setting offset might also be used. I just resurected one of mine that had a bad connection to the negative battery connection. Hard to connect to with regular soldering techniques. I mention the light range - film reciprocity will give more error than this meter!
Lots of luck. BTW, it can be used in reflected or incident modes using the sliding dome. LunaPro should be so good....