I'll pull out a couple of my Bibles tomorrow and have a look.

The problem is that the numbering of the psalms sometime differs between the Catholic translations and the Protestant translations. You want to be sure you're getting the right verse.

Redwolf

this one?
Create in me a pure heart, O God, and renew a steadfast spirit within me

Bedell:
Cruthaigh ionnam croidhe glan, a Dhé; agus athnúaghaidh ann mo mheadhón spiorad iomlán.
Cɼúṫaiġ ionnam cɼóiḋe glan, a Ḋé; ⁊ aṫnúaġáiḋ ann mo ṁéaḋon ſpioɼád iomlán.
(in Bedell’s Gaelic font typography some accents seem to be wrong, in Roman font they are (more) correct, whyever.)
So with corrected accents:
Cɼuṫaiġ ionnam cɼoiḋe glan, a Ḋé; ⁊ aṫnúaġaiḋ ann mo ṁeaḋón ſpioɼad iomlán.

The Gaelic font used in this forum is Bunchló Ársa.
But if you copy the following sentence and choose the Seanchló na Nod font (similar to the original one used in Bedell’s bible) this should be shown with the original "nods" (abbreviations) used in Bedell's typography:
Cɼúṫaiġ io0nam cɼóiḋe glan, a Ḋé; & aṫnúaġáiḋ a0n mo ṁéaḋon ſpioɼád iomlán.
and with corrected accents:
Cɼuṫaiġ io0nam cɼoiḋe glan, a Ḋé; & aṫnúaġaiḋ a0n mo ṁeaḋón ſpioɼad iomlán.
(0n would be a macron on the n (= nn), & would give a Tironian et (= ⁊= agus))

An Bíobla Naofa (here: 51:12)
Cruthaigh ionam croí glan, a Dhia, agus cruthaigh spiorad daingean as an nua ionam.
Cɼuṫaiġ ionam cɼoí glan, a Ḋia, ⁊ cɼuṫaiġ ſpioɼad daingean aſ an nua ionam.

Yeah, that's the verse. What's the main difference between the two versions you listed? Different dialects?

Here's what I came up with after downloading a seanchló font pack and retyping the passage from Bedel's for the formatting I want on the tattoo: http://imgur.com/Qk6Lqwt


This pack didn't have the accented n as in Bedel's text, but I believe I got everything else right for his version.