according to the SOS editorial folks and oft quoted data in books on MIDI, you'll be fine with up to three synths daisy chained. MIDI delay is caused by having to go through the data buffers in each synth where the data is looked at to see which data is relevant to the synth (eg everything on channel 5 is played, everything else is ignored).
You may (and I stress MAY) be lucky and find that 8 synths daisy chained work fine, but the best solution for any timing problems would be a MIDI thru or a MIDI patchbay unit, which essentially provides one in and several MIDI outs. It duplicates all the MIDI info at the outs and away you go. Various manufacturers provide units of this type and you'll find them on Ebay, amongst other sites.
If this fails, then it's a case of biting the bullet and getting a Midex!
Lots of Ataris which keep on going, 12 Kurzweil 1000 modules, a bunch of hardware synths. Still recording to tape -the old ways are best.....