I would surely go for the 855, it`s in another class compared with the 7 - 900 series. depending on how much money you are going to spend i would go for a 94 - 96 because of the design changes volvo made 94, it feels a bit more modern.
new hedlights and rounded of edges on the buttons and controls.
in EU tou will find this car with 2.0 w/wo turbo 126 ws 165 hp (not shure on the hp:s but close to those numbers anyhow) 2.5 w/wo turbo and 10 or 20 valve, 10 valve wo turbo 140 hp, 20 valve wo turbo 170 hp, 2.5 turbo 225 hp and the awd with a low pressure turbo on 193 hp:s, 97 in s/v 70 the 193 hp engine came without awd also.
the 2-7-900 volvo is based on the same engine/tranny and all and all is a base construction made in the 70:s, no bad words about these cars but a 850 is in another league because its a modern car developed in the 90`s.

Ever thought about 960? if youre still thinkin strong about rwd this s a nice car.

Claes
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V70 2,5T -98