I run a set of World Products Windsor Jr. Irons. I have had good success with the heads. They make great power for the price. The castings, as they come from the production line, have a lot of casting flash. If you want to spend some time, you can smooth this out. Also, the components included from World Products (such as springs) aren't all that great.
The heads I run are stage 1 ported from Keith Craft (
http://www.keithcraft.com/shop/shopd...asp?Search=Yes). They come pocket ported with a 3 angle valve job, 1.460 springs, chrome moly retainers and locks, studs, & guide plates for $899. That may be a bit steep for a set of iron heads, but these guys do great work, are easy to talk to, and they provide engines for some big names like Doug Mangrum. Keith says they typically see about 235CFM@ .500 lift on intake and 190CFM@ .500 on exhaust with the stage 1 work.
If you opt not to purchase a set of cleaned up heads, it's a good idea to replace the springs reguardless.
Here's the flow and tech information for the World Products Jr. and Sr. heads.
http://www.worldcastings.com/tech/windsorjrtech.pdf
http://www.worldcastings.com/tech/windsortechinfo.pdf
Hope this helps.
--nathan
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'91 GT, Coast 347, 9.5:1 compression, full intake, Wolverine 1087 cam, exhaust, Keith Craft ported Windsor Jr. Irons (235 cfm intake, 195 cfm exhaust), AOD, PI 3500 converter, Lentech valve body, 3.73's (4.10's in the works), and Yokohama ES100's out back.
Daily Car: '04 Infiniti G35 Sedan 6MT