Vintage Sony PLPS (SMPS) repair

[nyogo]

Hi!

I'm restoring an old Sony TA-F6B amp(European model), the power supply kicked out the bucket. A cap at the regulator part blown up(C604), killed some transistors around it.
Already replaced all caps, measured all transistors, I still have to check all resistors and diodes(but at first look they seems to be fine).
The original 2SC2023Os at the inverter are fine, also Q605, Q606, Q607, Q608 are ok.

The problem in the regulator part is with 2SC2023R (Q613), 2SC1810 (Q602), 2SA911 (Q603). I suspect that I should change all transistors in the regulator, at least Q601/Q613 to the same.

I have a few 2SC2023 (without R or O letter) but still doesn't find any info about the lettered versions, so don't know whats the difference and why it is only R type allowed in the regulator and R or O at the inverter.
(I found similar lettering for Fairchild KSC2335, where the R-O-Y mark the hFE classification and R stands for the lowest.)
Also if I change 601/613 to simple 2023, would it affect the other part of the power supply?(sadly I don't have that kind of deep knowledge about electroics or SMPS/PLPS)
Checked a few forums where some folks tried to repair same board with similar blown-cap caused issues, and it seems like the circuit is really sensitive for the right spec transistors.

Found some old datasheet for 2SC1810 but nothing for 2SA911.

It would be a really big help if someone could advice some replacements for 2SC2023R, 2SC1810, 2SA911. Maybe I could get some new old stock 2SC1810/2SA911 from eBay, but I would prefer some common off the shelf parts.

Attached the schematic from the service manual, marked the bad transistors.