ITB size is one indicator or u can open up the throttle plates and look into the intake ports...theres a difference in design between the ports of both engines...look up some pictures of that on google the check yours that will at least tell u if the head is also blacktop...if he didnt change the timing belt tensioner to 16v u will have an external tensioner on the intake side of the timing belt towards the bottome or u can pull a spark plug and shine a light down the hole see what shape the piston dome is also...silvertop has 5 valve reliefs on the pistons where blacktop has two

There is a difference in the amount of ribs above the exhaust ports.
I did a google search and this came up for a BT head

http://2.bp.blogspot.com/_b9O21vHYOxY/S ... 009360.jpg

And this is a silvertop head

http://images.trademe.co.nz/photoserver ... 603543.jpg