HELP: single front mounted i/c

am going thru the process of getting one for my 91gto. because its quite hard to get aftermarket front in NZ, i am going attempt to fit it into the factory front and mayb get it remoulded. firstly, if the factory spot lights are re moved i can fit an i/c max size mayb 700 - 750mm by mayb 300 - 340mm height ( havent got the guts to smack the hole in her yet!). i was wondering wat the difference is btween bar and plate vs tube and fin? is there any benifit to choosing one over the other? also, piping: wud it b better to have the inlets at the top or bottom and wats a gud size ( 3" too big )?