Italian baby fiat ebayer Pasquale -
the man for Panda 30 heads and good for other tuning kit such as brakes
Pros:
Knows his stuff
Reasonable pricing
Supplies full, refurbished heads/carbs including all the annoyingly hard to get bits like pushrod tubes and short studs
Speaks good English
Sends phootos of exactly what you are getting, before you pay
Accepts paypal
Replies to emails quickly
Cons
Can't think of any
You'll need to email him for what you want - the ebay shop only has bits and bobs
http://stores.ebay.co.uk/Ricambi-auto-e-moto-depocaEDIT: if you vote it would be good to have your opinion as a post, especially if "avoid" so we can be aware of problems and also know that you are not a spoiler/commercial competitor.