before you install the heads you can rotate the engine and bring it up on TDC but it does not time like the old GM engines do because of the balance shaft and it uses #4 cyl on TDC from what i read in the manual.
Got a serial number?
There is an early and late model GM 4.3L hyster used, we need to know the correct year.
Also if you can put your email address in your signature here on your forum profile located in the "my account" section.

I have some information that may be helpful :o)