Help with boost limit on modified engine please!

[s-express]

Hi guys, I'm a bit of a lurker but enjoy visiting and picking up useful info. This time, I feel I need to call on the collected expertise rather than exploit the search function:
I have a AMK engine that has had a lot of money spent on it by previous owner but then neglected and abused and I am now picking up the pieces and trying to make it good again.
Brief spec:
AMK block
AGU head
stainless inlet valves
iconel ex valves
Wossner rods
IHI VF34 turbo
ME7.1 Bosch ecu
Greddy BC
uprated fuel pump & injectors (unknown spec at present)

Now when I got it, the car wasn't boosting right, turns out the spring and sealing cup of the diverter valve were missing completely! So after replacing them, putting your foot down felt like a mule was kicking you in the backside. However, the Greddy was all over the place, peak boost was (according to the Greddy) 2.75 bar (40psi!!) anyway, played with the parameters and got boost down to around 1.3 bar and no harm seems to have been done to the engine.
Car is obviously nowhere near as quick as it was, pretty sure the engine mods are good for 400+bhp and the IHI turbo good for 340+ bhp.
Now just in the process of fitting a wideband lambda gauge (Stack) to ensure I don't run lean.
So my questions is; Once I have the ability to monitor by AF ratio, is there any reason why I cant just keep turning the boost up? Surely if I keep the AF richer than say 11.5, then I should be able to run the turbo to whatever boost it will let me have? Or am I going to grenade the engine? I can't help but think the turbo will run out of puff before I stress the engine too much, after all, the rods and valves are done?
Would love someone with the knowledge to let me know please!

Thanks guys....

 

[Samuealle]

Turning the boost up when you have no control of timing? Id avoid that.

 

[s-express]

It's been mapped by jabbasport at sometime in the past so presume timing will be safe?

 

[Samuealle]

Yeh but at what boost levels?

 

[s-express]

So would, say 0.2 bar make a difference to timing? Sorry, I'm still learning!

 

[Machine212]

Theres a place near me called area 52 autosport that does boost controller setup on a dyno for 75 quid. That way they can keep everything in check. Theyre a subaru specialist though. Id try and find a tuner near you that will set it up for you on a dyno rather than doing it blind.

 

[Samuealle]

Why not stop faffing around take it to someone whom knows what they are doing with these engines.

It's not a cheap toy you are playing with.