Pics

It's only a piece of ally with some holes in it!
Not worth me taking pics of mine as I modified it (one of the mounting holes on the TB was changed so one screw goes through that, the adapter plate & into the manifold

).
Here's roughly how to do it....
Firstly DO NOT drill the main hole untill the end :nono:
Make a paper template of the bottom of the original TB. Fix this to a piece of ally (I used 6mm as that's what I had available). Use this to drill the 3 holes to mount it to the manifold & countersink them ,make the holes only just big enough for the 3 countersunk screws you're going to use to pass through -6mm is also just thick enough to allow you to countersink the holes on the bottom for the TB locating tabs on the manifold (you will see what I mean when you take the TB off).
Make a paper template of the bottom of the 16v TB, lay this over the other template to get the 'best fit possible' so that the main hole lines up BUT the screws to fix the 16vTB to the plate don't interfere with the heads of the screws holding the plate to the manifold. Drill these holes not forgetting that they need to be smaller than the screw diameter as you will tap these holes so they are threaded.
Now drill/file the main hole to line up with the TB side & the manifold side, some of the sides are sloped hence not banging a big hole in it to start with (been there, done that

). You might need to enlarge the hole slightly in the plastic manifold -i did.
If the 16v TB didn't come with it's throttle cable locating plate you will need to screw a spacer plate to the 16vTB & use the Sei plate. Chose a thickness for this spacer & screw the Sei plate so that the cable will line up the correctly & that it is the correct distance from the TB.
Or if you can't be bothered with all this ask sparky5 how much he will charge to modify your existing Sei TB. (wonder if I will get commission

)