Hi. the P29 piston is Ok for a set-up. I check with a web to calculate the compression ratio. With the D15 block, D15 crank, D-15 rods ( 134mm) and the P-08 head ( D-15 Vitec/D16z6, camber volume 34.60cc) you get a 10.2:1 C.R. with the regular head gasket ( 1.2 mm ), good for regular gasoline. With the D-16z6 metal head gasket ( 3 layer , 0.9mm) you get 10.5:1 C.R. good for 91 oct fuel ( 95 oct RON ). With the D16y8 head gasket ( two layer metal, 0.6mm) you get 10.8:1 C.R., good if you plan to buy a hot street cam and 91 oct gasoline.
Do not use the D16z6 rods , they are to long 137mm for the D15 block ( C.R. will be over 11.5:1) and they can only be use in a D-15 Vitec crank from Japan because they have a bigger journal diameter.
The D16y8 head ( Vitec) have a smaller camber (32.80 cc ), so you get a higher C.R. Check the head code to be sure which one you have. If your head is from D-16y8 better used the regular head gasket from a D15 NON Vitec engine ( not metal, 1.2mm) for a 10.60:1 C.R.
You can check the C.R by youself in this Web: www.Zealautowerks.com/dseries.html