Later IPs have a port to access a timing lug. The port is on the outboard side of the IP coverd by a plug with a 17mm head. If your IP has a plug, you can eyeball timing. You can check the position of the lug with an IP locking tool which is a device that engages the lug to hold the IP shaft against the case when you intall the IP at a prescribed cam position. You can probably do just as well with a mirror or a wood dowel (to take an impression of the lug) or a piece of wire (to feel for the lug).

I don't know that using the lug as a timing mark provides more accurate results than the drip method. Seems to me that unless the cam is timed spot on with the crank then +/- 1 degree of IP timing isn't going to make much difference.

Sixto
95 S420
87 300SDL