I have a 8-71 littlefield blower and intercooler i am going to put on my 540 tall deck i need a intake manfold for it. are thay all the same

No. Most are similar but their are some custom high rise blower manifolds which have better flow because of a straighter shot into the head. The engines I see these on are very serious (1000 plus HP). I assume yours isn't too radical with an 871.