Would +35 work on a 19 x 9 in front or does it have to be +25 for that size?  Planning 19 x 10 +35 in the rear.

This is for a 1995 Twin Turbo, lowered mildly on coils, 13" Rotora BBK, adjustable front camber and caster.  Planning 245 35 R19 front and 285 30 R19 rear. 

I'm hoping to run as much offset as practical in front to preserve steering feel but I don't want to run spacers if I can help it, hence the question about +35 in front.

Sorry if this has been discussed before.  Newbie here.

35 offset "should" work on the front - but it will depend on the spoke pattern, as to whether they will clear the brake calipers.

I initially tried 35 offset when I bought my Japan Racing wheels. Admittedly they were 8.5 x 18, but the flat spokes would not clear the stock calipers, so I had to go 25 offset instead. 35 on the rear will be fine though.

My new wheels are 32 offset on the front (again 8.5 x 18), but the concave spokes give plenty of brake clearance. I have 9.5 x 18 on the rear, with a 35mm offset and they fit fine, the tyres (265/35) sit right on the arches. 

It's not just offset to think about but also spoke profile (especially with aftermarket BBK's). The diagram below illustrates why:

Yup - exactly as Andrew says!!