Our island is the same height as the perimeter cabinets.

What are you going to use the island for? That determines the height of any countertop. We love our island which is 32 inches with a cooktop and used for plating a meal. I'd hate it if I had to prep at that height.
Unfortunately, the North American standard of 36 doesn't work for everything and we learned from our european kitchen to vary the heights according to the use.

I agree with Moebus - determine what you want to do on the island and then figure out the height. You said you wanted seating on two sides - so do you want more of a table height or a counter height or something in between? What else will you do on the island?

FWIW, I'm planning my island at 34" because I intend to prep on it and that's the right/comfortable height for me.

Where will the seating be? Based on your stated dimensions, it sounds like the two short ends, is that correct? There is no room for seating on the long sides unless you do not plan to have any cabinets in the island...

If you have standard 24" deep cabinets in the island, to have seating on the back side, the island will need to be at least 41.5" deep:

1.5" counter overhang + 24" deep cabinets + 1" decorative panel/decorative door + 15" seating overhang (clear space) = 41.5"

Skimping on seating overhang will not help - people will stick out into the aisle just as much even with a shallower overhang - they'll just be very uncomfortable while sitting there.

If seating is on the two short ends, then plan the overhangs accordingly.