A propeller pitch question

The PLANE - RV-6A still in Phase I testing, now with gear leg, intersection fairings and Sam James wheel pants. No other speed mods and a stock O-360-A1A with a carb and 2 magnetos.

The PROP - Sensenich PROP 72FM8S9-1 (83)

I notice Sensenich rates this as a "standard" prop for a 180 HP -6A, while Vans sells the 85 inch pitch version.

I did some high altitude flying today (cooling off a bit to 44F

) and tested full throttle speeds.

At 12,500 ft I got 2710 rpm and 168 kts TAS

At 13,500 ft I got 2670 rpm and 166 kts TAS

So it seems like my full throttle 2700 rpm number is essentially 13,000 ft. and 167 kts (191 mph)

Note that today this 13,000 ft pressure altitude was about 15,200 ft. density altitude.

Climbing the last 1,000 ft at 100 kts IAS I was at 700 fpm.

Above solo with 3/4 tanks and an estimated weight of 1470 lbs.

At this time of year I'm taking off at 5,000 ft DA early in the morning so don't know the effect of pitch at lower altitudes.

**So the questions are - **
Should I stay with 83 pitch or have it re-pitched to 85, the same as Vans sells?

If I change, what effects would I see?

Are the "full throttle rpm" recommended altitudes usually quoted as pressure altitude or density altitude?

PS - the TAS speeds are not quite fully calibrated yet, but are probably within 1 to 2 kts accuracy as I'm slowly adjusting the static port "bumps".

PPS - not ready to switch to Constant Speed yet, so please keep replies to Sensenich FP props.