I know it will be expensive but I suggest doing some research on how much it would cost you to land a DTM (Down The Middle) shroud from
www.aircooledtechnology.com - they have been developed and refined with actual research (dyno time) and are viewed widely in the TIV upright community as the best cooling option at the moment. See
www.shoptalkforums.com (type 4rum or aircooledtechnology forum) for more details.
I have used one of the locally made kits and although happy with the fibreglass thickness and quality of the product, I have had my fair share of problems and hassles getting everything to fit right.
But on a budget, consider Joe Cali's upright conversion manual which you can modify stock type IV cooling tin to work (with some welding and modification) - by far the cheapest solution but will be labour intensive.nn[ Edited on 4-8-2005 by Dasdubber ]