Brad ,
I ran a similar Dynamic/Lupo to you for years stalled around 48/4900 . This was with both 440 and 505 footbraking .
Now with transbrake I have a A1 Performance 8" unit , stalled at 5800 with original 505 and 440 . When I went TF270 head stall went to 6000 , but car went 0.25 faster so the heads obviously helped the motor HP wise.
Drives fine daily . Even drove to a race in Mildura on the other side of the state - 12 1/4 hours on the highway no dramas . Tis was 2 weeks ago .

Tex