Use \ldelim with tall rows

Use \ldelim with tall rows

I would like to put a brace in front of some table rows. I found a similar question here and in an answer the use of the bigdelim package is suggested.
The problem is, it does not seem to work if a row contains a lot of text that is wrapped to multiple lines. Here is an example to illustrate the problem:
\documentclass{article}

\usepackage{multirow,bigdelim}
\usepackage{blindtext}

\begin{document}
  \begin{tabular}{ccl}
    \ldelim\{{3}{3mm}[a] & \ldelim\{{1}{3mm}[x] &
    \begin{minipage}{0.8\textwidth}
      \blindtext
    \end{minipage}\\
    &\ldelim\{{1}{3mm}[y] & More text\\
    &\ldelim\{{1}{3mm}[z] & More text
  \end{tabular}
\end{document}
This produces the following:
What I would like is to let the brace x span over all of the lorem ipsum text and the brace a to span over all three table rows.
How can I achieve this (using \ldelim is not a strict requirement, but I like the syntax)?
EDIT: Note that the minipage I use to hold the text does not only need to contain text but also e.g. a tikzpicture or some small tabular (I'm not exactly sure yet…). So the minipages height does not need to be a multiple of the height of a line of text.