if your gonna build a 1.5/6 then you have to use the 1.5 pistons and notch them. they are not the same size wrist pin or compression height as 1.5 pistons. it wont have enough compression to run if you get the 1.6 pistons on the 1.5 rods. as long as you use a 1.5 bottom end, 1.6 block, and 1.6 head, you should be good to go tho. it shouldnt be too hard to start. but if you added a 1.9 head, it will be real hard to start when cold. just make sure you find a turbo block, thats the only way its really worth building one of these.
im running a full 1.5 turbo engine. built it myself. has a VNT off a 01 ALH on it. and a gasser intake mani from a digi 2 jetta. with a 1.6 turbo pump and injectors. it hauls @ss..
have any questions, im sure i can help out.