Micke,
First, welcome to the Forum
You will find a lot of help here.
Congratulations on your buying a ‘69T.
Coupe or Targa?
Pictures please.
Where are you located? Budapest?
Tell us more about your 911 and your intended use.
When considering ‘more power’ check your budget.
It will be a fun and satisfying project if it is budget-constrained.
It gets uncomfortable if you get half-way and at the budget limit.
That said, John is giving you good advice above.
Start with another engine.
This has several advantages: you can continuing driving while you build an exchange engine at your leisure.
This also allows you to source all the ‘right’ parts at the best cost. Being in a hurry costs more.
The 3.0SC is the easiest solution. You can even use your exhaust, carburetors, clutch (sorta), fan shroud, wiring, etc. on a stock 911 SC engine. This makes installation easy and the engine will appear (close) original.
A 3.0 is at the limit (perhaps above) for your type 901 transmission. Many doing this conversion install a type 915 transmission.
A 2.7 is more suitable for your transmission and is a lighter weight engine. The difficulty is finding a good, properly rebuilt engine. Of course the ‘ideal’ is the type 911/83 from the ’73 Carrera RS 2.7
Big bucks but great fun.
You also need to consider the rest of the car.
More power can need improved brakes, suspension, tires, etc.
You will find all the answers (and more) here.
Best,
Grady
PS: You can have the Moderator move this to the 911 Technical Forum. You will get more responses there.
G.