paper negatives

I always wanted to try this -

Kentmere VC Select RC paper used instead of film in my 5x4 Tachihara.
Pre-flashed under the enlarger for 0.3s at F/11.

Exposures of 1s, 2s, 4s, 8s, at F/32.
By my humble estimation - and choosing the 4sec exposure to work with - that rates the paper at a lowly ISO 0.75, slower than the ISO3 normally quoted.

Perhaps I need a longer pre-flash?