PICUS time as PIC for restrictions?

[OhNoCB]

I understand when PICUS time can be logged and I understand that you can use 150 PICUS hours for ATPL issue.

What I was wondering was with regard to this:

(ii) when operating on a multi-engine type under Instrument Flight Rules (IFR), the pilot has a minimum of
700 hours total flight time on aeroplanes which includes 400 hours as pilot-in-command (in accordance with
the requirements governing Flight Crew Licenses) of which 100 hours have been under IFR including
40 hours multi-engine operation. The 400 hours as pilot-in-command may be substituted by hours operating
as co-pilot on the basis of two hours co-pilot is equivalent to one hour as pilot-in-command provided
those hours were gained within an established multi-pilot crew system prescribed in the Operations Manual;"

For the 400 hours PIC, can you substitute PIC hours with PICUS ones on a 1:1 basis?

I can't find a direct answer to this anywhere. For CPL issue the CAA accepted my (small amount of) PICUS time towards the 100 PIC for licence issue, which to me implies that it's possible they could view it as the same, but at the same time - the fact that only 150 PICUS hours can count as PIC for ATPL issue makes me wonder if there would be a restriction.

Ringing the CAA provided no answers.

Anyone know (and even better - have reference?)