Why not make it using this,

http://bbloomf.github.io/jgabc/psalmtone.html

N.B. The Benedictus can be chosen as one of the psalm options

Anyway here is the Gabc code as made on the above link,

name: Benedictus-8G;
initial-style: 1;
annotation: 8.G;
user-notes: Benedictus.;
centering-scheme: latin;
%%
(c4)Be(g)ne(h)dí(j)ctus(j) Dó(j)mi(j)nus,(j) De(j)us(j) Is(k)ra(jr)ël :(j.) \greheightstar(:) qui(j)a(j) vi(j)si(j)tá(j)vit,(j) et(j) fe(j)cit(j) red(j)em(j)pti(j)ó(j)nem(j) ple(i)bis(j) su(h gr)æ :(g.) (::)
2. Et(g) e(h)ré(j)xit(j) cor(j)nu(j) sa(j)lú(j)tis(j) no(k jr)bis :(j.) \greheightstar(:) in(j) do(j)mo(j) Da(j)vid,(j) pú(j)e(i)ri(j) su(h gr)i.(g.) (::)
3. Si(g)cut(h) lo(j)cú(j)tus(j) est(j) per(j) os(j) san(j)ctó(k jr)rum,(j.) \greheightstar(:) qui(j) a(j) sǽ(j)cu(j)lo(j) sunt,(j) pro(j)phe(j)tá(i)rum(j) e(h gr)jus :(g.) (::)
4. Sa(g)lú(h)tem(j) ex(j) in(j)i(j)mí(j)cis(j) no(k jr)stris,(j.) \greheightstar(:) et(j) de(j) ma(j)nu(j) óm(j)ni(j)um,(j) qui(i) o(j)dé(h)runt(gr) nos.(g.) (::)
5. Ad(g) fa(h)ci(j)én(j)dam(j) mi(j)se(j)ri(j)cór(j)di(j)am(j) cum(j) pá(j)tri(j)bus(j) no(k jr)stris :(j.) \greheightstar(:) et(j) me(j)mo(j)rá(j)ri(j) te(j)sta(j)mén(j)ti(j) su(i)i(j) san(h gr)cti.(g.) (::)
6. Jus(g)ju(h)rán(j)dum,(j) quod(j) ju(j)rá(j)vit(j) ad(j) A(j)bra(j)ham(j) pa(j)trem(j) no(k jr)strum,(j.) \greheightstar(:) da(j)tú(j)rum(i) se(j) no(h gr)bis :(g.) (::)
7. Ut(g) si(h)ne(j) ti(j)mó(j)re,(j) de(j) ma(j)nu(j) in(j)i(j)mi(j)có(j)rum(j) no(j)stró(j)rum(j) li(j)be(j)rá(k jr)ti,(j.) \greheightstar(:) ser(j)vi(j)á(i)mus(j) il(h gr)li.(g.) (::)
8. In(g) san(h)cti(j)tá(j)te,(j) et(j) ju(j)stí(j)ti(j)a(j) co(j)ram(j) i(k jr)pso,(j.) \greheightstar(:) óm(j)ni(j)bus(j) di(j)é(i)bus(j) no(h gr)stris.(g.) (::)
9. Et(g) tu,(h) pu(j)er,(j) Pro(j)phé(j)ta(j) Al(j)tís(j)si(j)mi(j) vo(j)cá(k)be(jr)ris :(j.) \greheightstar(:) præ(j)í(j)bis(j) e(j)nim(j) an(j)te(j) fá(j)ci(j)em(j) Dó(j)mi(j)ni,(j) pa(j)rá(j)re(j) vi(i)as(j) e(h gr)jus :(g.) (::)
10. Ad(g) dan(h)dam(j) sci(j)én(j)ti(j)am(j) sa(j)lú(j)tis(j) ple(j)bi(j) e(k jr)jus :(j.) \greheightstar(:) in(j) re(j)mis(j)si(j)ó(j)nem(j) pec(j)ca(j)tó(j)rum(i) e(j)ó(h gr)rum :(g.) (::)
11. Per(g) ví(h)sce(j)ra(j) mi(j)se(j)ri(j)cór(j)di(j)æ(j) De(j)i(j) no(k jr)stri :(j.) \greheightstar(:) in(j) qui(j)bus(j) vi(j)si(j)tá(j)vit(j) nos,(j) ó(j)ri(j)ens(i) ex(j) al(h gr)to :(g.) (::)
12. Il(g)lu(h)mi(j)ná(j)re(j) his,(j) qui(j) in(j) té(j)ne(j)bris,(j) et(j) in(j) um(j)bra(j) mor(j)tis(j) se(k jr)dent :(j.) \greheightstar(:) ad(j) di(j)ri(j)gén(j)dos(j) pe(j)des(j) no(j)stros(j) in(j) vi(i)am(j) pa(h gr)cis.(g.) (::)
13. Gló(g)ri(h)a(j) Pá(j)tri,(j) et(j) Fí(k)li(jr)o,(j.) \greheightstar(:) et(j) Spi(j)rí(j)tu(i)i(j) Sán(h gr)cto.(g.) (::)
14. Si(g)cut(h) é(j)rat(j) in(j) prin(j)cí(j)pi(j)o,(j) et(j) núnc,(j) et(j) sém(k jr)per,(j.) \greheightstar(:) et(j) in(j) sǽ(j)cu(j)la(j) sæ(j)cu(j)ló(i)rum.(j) A(h gr)men.(g.) (::)