Hi Waray65,
I went through the same. Although I was getting back into short boards after a long break of about 20 years. I surfed a single fin in late 70s then a 7ft epoxy surftech in 2001 to 2012. Too much volume to duck dive. I am guessing about 45 litres. Then to SUPs & short boards. I got a 6ft 38 litre all rounder which is just about right for my 80 kg weight. 58 years of age, fit but fairly weak paddler that takes late drops. Lol.
I am a cruiser & carver more than a bruiser shredder.
My favourite board is a Sunova Soul at 6ft 6" about 42 litres. It flys as a single fin & paddles & catches waves with ease. But! Its not a performance board for shredding. In saying that. My mate in his 30s who is a shredder & powerful paddler had a go on it & loves it. He normally rides boards at 5ft 8 to 6ft.
What I would recommend to any surfer that has a few years experience is to improve on their favourite board. That is you mentioned more paddle speed. Maybe more volume or width or length or flatter rocker or all four on your favourite all rounder. But be mindful on volume for duck diving. Which would be my last choice.
For your weight, age , paddlepower I would recommend anything from 6ft 3" 38 litres minimum to 6ft 6" 44 litres max. Somewhere in between like 6ft 4" 42 litres ideal. But the larger board would be more easy & comfortable to get onto waves. The rest would be board shape & fins.
So many variables that you could take to a shaper for your best fit.