I would go for the celica lump. Basically parts are easier to find, plus you dont need to do extensive work to unleash the power, just a few tweeks and shes good for about 330, plus the one you have in mind has history, yet the tezza one has none, which is a risk. We helped sort a customer with a few bits - celica GT4, mongoose exhaust, decat pipe, Apexi valve controller and a fuel pressure regulator, its now running 330bhp and 18psi, which is aboout at its turbos max and the bottom end is nearing a danger zone.
The tezza lump is a straight forward mod, but as you know is alot more expensive to get anything from it.
With the whole project possibly costing a few quid anyway, I would go with the celica power plant as replacement parts are a damm sight easier to source.
Thats just my opinion