Need exhaust pipe for my Ranchero what Size

I have a '62 Ranchero just got it running ( 4.1 X-flow). I have the exhaust header pipe from my 170 on it . Will this work or does the diameter need to be bigger. Now that it runs it seams to be restricted. Maybe one from a granada with a 250 and bigger diameter.Thanks for your help.Ken N.

What cam are you running? 170 exhaust is too restrictive.
If you are going to run a single exhaust with a non-stock cam, you need a 2.5" pipe/muffler.

Ya long day , I realized that it is from a '78 Fairmount which I think that is 1 7/8 . which will be ok for now . Thanks for you help before I put any miles on it I will change it.On to the next problem. Ken N.