I've just dedicated one camera body (Nikon FE) to infrared film.Mounted an 89b gell filter between the film rails and I'm all set to go.
How does ASA 100 on a bright sunny day sound?
Like a good place to start but I suggest you bracket your first roll +/- 1 or 2 stops and see which exposures YOU like, no one here can know this or the variables of your shutter/metering technique/film processing etc.
More xeposure will give lower contrast (due to highlight compression on the film shoulder) and more grain and less exposure will give the reverse with some risk of loss of shadow detail (which normally seems acceptable with prints from HIE negs).
I scaned a few frames and here is one of the better shots.Filter was mounted on the film rails and I set the speed to 50 ISO.Developed in D76 full strength for 9 1/2 mins.
Looks like a Sugar Maple in that cemetary. If so, they're the best for infrared. Good photo, too! I'd say your EI of 50 was spot on. I use EI50 for Ilford SFX.