I have a CHP 347. I had them do somewhat short of a short block since I needed a block. I received excellent customer service both before and after my purchase. The quality of workmanship on the blockwork and assembly was excellent. I now have 15k+ hard miles on the motor and have no problems. Mine was also ready 5 days earlier than promised
I looked at CHP, but now I'm talking with DND Motorsports. They offer a 342 with fully forged steel bottem end and forged pistons, plus full roller moter up top. All quality parts long block for $5000 that is 500hp naturally aspirated and will support 680hp blown or juiced. Several 351 stroked combo's as well. I'm going to order mine soon. Check them out at dndmotorsports.com. Not trying to plug them, just checked out lots of companies, and they seem to offer quality stuff. Heard good things about CHP as well.
I have not used CHP, however based on personal expereince with my own 408c stroker I can tell you to fain away from speedomotive in CA. When dealing with whomever is building your kit after you give them all the specs if they say they are going to have custom piston made, make sure you ask to be copied in on all communications...Speedo faxed the wrong specs to the piston manufacture and I still had to eat the cost of replacing the pistons and pins (and a bunch of other stuff that broke because of the error) when I finally figured out what the heck was wrong with my motor.