The rotary numbers can be exceeded. With the 2551 I've been known to stick 1 litre of fluid in the thing. If you're worried if the tank will handle 450ml just stick some water in it and test it out. Sorry best I can do.
In the unblinkingeye.com article Sandy King cites 50ml Pyrocat HD per 4x5in film. I have read in a subsequent post from sandy to use a 1.5:1:100 ratio in the Jobo. I have been using 300ml of 1.5:1:100 in this Jobo tank using continuous agitation with up to 6 5x4 in the tank with no noticeable problem. I also use the metol variant of Pyrocat.
50-60 ml of developer per 4X5 sheet is about ideal.
If you are developing for silver printing the 1:1:100 will work fine. However, if developing for alternative printing, where you need longer development times for more contrast, use a 1.5:1:100 dilution. (That would be 15 ml of A + 10 ml of B in water to make 1000 ml. )
FWIW - I use the Job for standard inversion aggitation and find that 1.25L is necessary to completely cover the film - and give even stain. When I used 1L, I had an edge of the 4x5 film that did not stain properly and the same with the fixer.
I use a CPE+ with lift and the 2521 drum to develop up to twelve 4 x 5 negs at a time with 580 ml of developer (TMAX-RS diluted 1:9). Given the JOBO's continuous agitation I have never had any uniformity problems.
JOBO warns about undue motor wear when using larger developer quantities with this tank/film combination, and thus have limited my quantities accordingly.