if you still need a topographic map i recently ( in February ) completed a massive 12 gig ( 131072 x 65536 Px. ) RGB image of the SAR radar
and a 4 gig 16 bit topo Height map( 65536x 32768 Px.) reworking the SAR data to get the height data from it
if people want i can resize it down
some links to images OF it
the C-1 compressed Magellan SAR DATA ( destripped )

http://www.imagebam.com/gallery/f3bc...72twzupqy07sj/
the Topo Height data

http://www.imagebam.com/gallery/gd89...06292pigyou39/
rendered Venus Height data
http://www.imagebam.com/gallery/tv28...jwc99c254uzl1/