You're not so much checking IP timing as timing advance. The FSM has IP advance curves and specs.

Here's one - Ferret Instruments , V765-01 Diesel Injection Detector / Timing Adapter - 765

Here's another - http://buy.snapon.com/catalog/item.asp?search=true&item_ID=645205&PartNo=MT257&group_id=683096&supersede=&store=snapon-store&tool=all
Sixto
87 300D