b and m megashifter nightmare

My car is about ready to go but I am stuck on the shifter. This shifter came out of a 64 cuda I used to have with small block. My new barracuda is also a small block with a 904. When it was in the 64 it seemed to shift fine. But it was in that car when I bought it. I have it set to where both adjustment points ( swivel nut and cable barrel) are right in the middle of their range. I set shifter in park and pulled tranny shifter arm into park ( towards back of car). Swivel nut came into shifter arm hole nicely, but when I shift the shifter to first it doesn't quite seem to make it, almost but not quite.
The cable doesnt seem to be melted and it travels nicely in the housing. I have the cable installed with about the biggest , smoothest loop I could make. I have the cable housing protected near exhaust with 2000 degree heatshield tubing. Is there a special shifter arm I am supposed to be using? The one on there is just the stock arm. Any other ideas?
Bonus question: why when you click through the gears down below with the shift arm, why is there 7 positions rather than 6, as in PRND21 ?
Thanky, Neal

There is an arm that came with it different from stock and I always set mine in neutral and adjust the cable so it drops right in the hole without effort.

First off, you might be feeling the linkage traveling past park (which they do)
It is actually in park but the lever can travel farther.

Most aftermarket kits have a linkage arm that goes with their kit, so the geometry and travel is right for their shifter.

And while I was typing chryslerfat mentioned putting it all together in neutral.
A good way of doing it because the trans and linkage are both in their center of travel.

If you can figure out what it needs you might be able to mod your lever to fix the geometry issue, or you can contact the manufacturer and order the lever that is supposed to ship with that shifter.

I have a Hurst Promatic 2 and use a B&M cable for a completely different shifter because Hurst only has a 5 foot (WAY frickin long) cable and B&M makes a cable that fits and is 3 feet long.
Shifter issue's suck.

We used a late 60s vintage Mustang shifter in a TA Challenger that by necessity had to be reconfigured to a 727. Put a couple new kinks in the shifter rod, bolted it down, off it went.

No a stock shifter arm will not work. Takes the special B&M shift arm for correct geometry. There's 7 positions because it's made as a universal shifter that'll work on 4 speed OD transmissions

Yeah - as above. You need the right lever for that shifter. Or do what I've done and modify your original lever to move the right amount for each motion of the shifter.

X2, IIRC the B&M shift arm is slightly shorter than the OE arm on the trans, thus moving the shift control valve further per linear movement of the cable...................

Decades ago when B&M ratchet shifters were in their infancy I installed one in my Ranchero, along with a 351W and a C4. I know WTF was i thinking? It was a 289 4 speed to begin with . That shifter linkage was just a wee little bit short, as far as the propper leverage for the C4. It always took a little nudge after the ratchet did its thing to get it in the right hole. The B&M lever was out of room to move the cable, so I welded the hole up and drilled a new hole about half a hole farther from the shaft. It was a good guess, worked fine after that. I quickly tired of the C4 and put the 4 speed behind the 351 and the fun was on . My old man just shook his head

I put an a body shifter int a 59 full size with a 727 from a truck.
It gave me fits, bending welding and doing over. I couldnt get the ranges close enough to work. After day 3 i drilled a hole in shifter arm-shifted into low and moved rod along shifter arm until it was about centered on arm.it was about 1/2" in from original hole. Everything was golden after that.

Transmission Lever for Chrysler TF727 or 904 Automatic Transmission - B&M Transmissions, Shifters, Torque Converters, Diff Covers, Coolers

May find it at summit or jeg's too..