Is my 340 stroked

That comp cam xe268h you have needs more converter. I know they say 2500 but it will be lazy on the bottom and you will never have any usable low end. At least 3000 stall. I've been down that road. Really a GOOD 3500 stall and a cooler. Then you can tune it. You will have to work on the ignition timing as well. Base timing will most likely be around 16. Lock out the mechanical advance to a total of about 36. Some will say no vacuum advance, try it both ways. Myself I use it on a street car. That 650 will feed it just fine. That should get it the ball park.