Mine was doing the same thing, read the article above and checked the plugs,they showed lean. Re-jetted the carb to 68 primary, 76 secondary and instantly no bog!

I have my primary jets currently at 70 primary, with the secondary still at 76, my cam is a little larger than yours so I had to drop the power valve to 2.5 (usually you want your power valve at half your idle vac) you may want to drop yours to 5.5, if it needs it. You want the power valve to open at WOT, not before or you'll get a stumble from it before the secondaries open. When the power valve is correct you 'll feel the secondaries open without any stumble and you'll know when they open. Mine runs real good now and plugs read correct color. You better be holding on now when I accelerate. LOL

Also make sure you have the accelerator pump adjusted correctly. Mine was way off, it had a big gap between the plunger arm and the actuator at idle. Set it so actuator (bolt with spring) contacts the plunger arm firmly at closed throttle (idle), then hold the throttle at wide open and make sure there is at least .020 between the actuator and the plunger arm, should be able to slide the feeler gauge in with only slight resistance (this must be done at WOT).