Topband: Few questions about RX Ant preamps

[Edward stallman]

Looking at the W7IUV preamp kit sold here 
http://www.mtmscientific.com/preamp.html
<http://www.mtmscientific.com/preamp.html>

I would like to place the preamp at the RX Antenna (YCCC 9 Circle ) 
because of the 450 Ft of RG6 from ant to shack . The W7IUV preamp is 50 
ohm so not sure if it's ok to use at the Ant? Or if I'll be just fine 
using the preamp in the shack after the 75 to 50 Ohm transformer ?

Can the input and output be easily changed from 50 to 75 Ohm ?

Does anyone sell a RX Preamp with 75 Ohm in/ output ? Need IP3 of 30dbm 
or better .. I know DXE has a nice preamp but it's designed to add other 
boards that I don't need .

Thanks Ed N5DG