Which Weber do I need?

Hi there, I have a 1990 1.8 clipper auto with the original pierburg carb. I'm looking to change to a Weber as I'm getting so much grief with the Weber. There just seems to be so many options for engine size, automatic & manual etc. I obviously don't want to buy the wrong one so was hoping you guys could point me in the right direction. Also what is a reasonable price to pay?
Thanks guys

Meant to say, 'getting so much grief with the Pierburg'.

You need 32/34 dmtl for an automatic.
Price looking approx £250

This seller has superb service and guidance if you need it.

http://www.fastroadcars.co.uk/shop/index.php?act=viewProd&productId=32

It states in description more information as regards the auto version you require.

Best wishes