700r4 shifting problems and swap advice wanted

[Madtrucker]

I recently bought a 72 blazer with a 350/700r4/np205. According to the spid it originally had 305/4spd/np205. The 700r is giving me problems with short shifting from 1/2 and not up shifting into 3rd. There's no slipping or high reving it just stays in second and drives until I back off to keep the rpms reasonable. I have re geared to a 4:56 and realize the governor needs calibrated but don't see how that will fix 3rd gear. At wot it shifts at about 2400. All the trans shops are 3-4wks behind and I'm trying to keep my blazer going for the season. If no one can help it's on to plan B.

Plan B would be to swap the 700 for a 350, my question is how can I tell if my 205 was mated to the 4spd or came from a 350 trans. I don't know what was modified to fit, the 700 or the tc. All I know is there is a advance adapter spacer between the to. I'm not looking to spend $1700 or I'd have the 700r4 rebuilt so any help would be appreciated.

And I've looked locally for a 350/205 combo with no luck.