Exhaust manfold question

I am currently building a 300 and I have the 64 aluminum heads and intake manifold for the top. I see that headman makes long tube headers that are for the 1970-74 Rover 3.5 / 215. Question is will these headers bolt up to the 64 300 aluminum heads?
215 and 300 had same exhaust manifold bolt pattern ??

 

Yep, but they may not fit your chassis without modification.

 

Ok so it is safe to assume that the exhaust ports are the same size or very close to the same size ?

 

Smaller but bolt pattern the same. Probably 1.5" tubes.

 

Right so thats my concern bolting the headers up to the 64 heads. Are they are gonna fit and cover the exhaust ports

 

Should be fine with the 64 aluminum heads. A lot of the MG guys reused the headers from the 215 with 300 64 aluminum heads, Your bigger problem is they were made to fit the Range Rover.