Hi Jim how are ya ,Nice Daytona.
I saved this article a while back , it might have what your looking for.
Its a 505 build that used a external pump / filter system , the articles was done in 2010
so hopefully the pump parts are available.

https://www.americanmusclecarsaustralia.com/forum/index.php?topic=3526.0

1971 duster twister 440, 3380#,509 M/P hyd,906's,full Exhaust,11.06@117.46 1/4,6.95@ 97.03 1/8,1.497 60ft.....