D330 pre conbustion chambers question

Hi guys i have a 955h with the d330 engine and recently purchased a second hand head which has been reconditioned the problem is the pre cups theads in the new head are smaller im guessing the head was off a d4c 40a as the head also came with a decompression rod mechanism which the 955h does not have what im wondering is do i simply purchase d4c pre cups or do i need to re thread the head to fit the 955 pre cups?

Early chambers for the D330a work up until 60A9889 (5S1833). Above 60A9890-up uses (5S1822). Head swapping should match the s/n range. I don't know if you can interchange by swapping chambers. Close comparison inspection and dimensions would be required. All heights, diameters and seal locations would need to be checked.

Hello
From what I can remember many years ago the non turbo engine (D330) were not fitted with valve inserts
and at the Dealer we would machine and fit insert to all parts exchange heads.
Therefore D4C & D did not have inserts fitted from factory?
If not going to use your machine in anger then possibly should survive if not fitted.
Also the pre-com chambers can have different size openings, i.e. orifices into the combustion space.
Best regards
Gary