Hello to all - i have a 400 sbc 2 bolt mains. i wanted to know if it is possible to use longer 6.00 rods and new pistons on my stock 400 block vs the 5.7 rods. Bore size is standard as well 4.125. Thanks  

Yes, just be sure to get pistons for a 6 in rod.  

Any ideas on a good brand of rod and piston,and can i use dome or should i stay with flat top. Here's my plan.

400 small block ( 2 bolt Mains)
4.125 STD Bore  (Stock)
5.750 Crank   (stock)
New 6.00 rods
New Kieth black Dome pistons  (Std Bore)
New clevitte main/rod bearings
Set of Edelbrock 202/160 heads
Jr. Victor Intake
600 cfm Edelbrock carb

Need a good cam combo: thinking of Comp or Edelbrock any suggestions.

Feel free to give advice on any thing wrong in my Plans  

If you want to run pump gas you will definitely need a dished piston.

I would use around something around a Comp XE274 or maybe one step smaller.

By the way, the stroke of your engine is 3.75 inches, If it were 5.75 in. you would have a diesel-like 615 cubic inches.  

What is this engine going to be used for?  

Sleeper / Sunday Driver - 1984 Camaro z28  

99% of 400 blocks need to be bored. The bore may look good but most are out of round especially on 400's so have a machine shop check your block. Also have it magnafluxed or sonic checked for cracks. You said you wanted to use Kieth Black dome pistons. As Gib stated, you will need a dish to run pump gas. Scat sells a good economical rod. Personally i wouldnt run the Victor Jr. You would probably be better off with the Performer RPM AirGap. As for your choice of carb, im not a big fan of Edelbrocks but some folks on here might disagree. I would use a Holley or Speed Demon 750.