IIRC, the consensus on the Strokers' Group site was that the Speedomotive "kit" wasn't worth the money and you can do what they do for less.
There are two basic alternatives for a stroker, both using a 258 (4.2L) crank shaft:
(1) Use the 258 rods with stock 4.0L replacement pistons. The downside to this is that pin heights are slightly different and you get a very high compression ratio. They advise running a cam with more overlap than stock to bleed off some cylinder pressure to compensate. Recently, a couple of guys have found that Silvolite has a replacement piston with enough meat on top that you can increase the dish to reduce compression ratio.
(2) Use 4.0L rods and get custom pistons. Going this route you can get a stock compression ratio, but the pistons will be forged and tend to make noise when cold. Some people don't mind this, others find it objectionable. The Accurate Power kit uses this approach and is considered on the Strokers' Group to be the most reliable and cost-effective kit.
