I can see the remains of the decomp there. Can you tie it open just for now.
Those motors never kick back quite as visciously as the earlier motor, maybe different kick gearing i don't know.
But set your points timing to 2.5mm btdc on the 360 & will soften the kickback a little.

I ended up making a device that clips on to the decompressor to manually operate the plunger. It works great, though I can't use the standard rubber cover. It'll do until I buy another decompressor cable.

I have no idea where the timing is at currently. It runs fantastic and doesn't ping, so it can't be too far off.