I used the 7135 over 25 years ago, with a small 6502 and VIA chip, sharing 5V supply, for different thermometer sensors, PT100, special T-diode, a AuFe/Ni thermocouple.. required a 7650 chopper amplifier for x100 gain for 1µV resolution.. as long as the sensor is isolated from the digital ground there's no problem with ground loops, worked very well.
I used the counting method, with a gate, very easy, as described in the datasheet, with IRQ and FP arithmetic, everything written in assembler.
I still have this PCB /module somewhere.
Frank