I have a very old HW, some minor pitting here and there.  It is a standard straight grip, single trigger hunting rifle in 38-55.  Decent trigger, and locks up tight.  2" 5-shot groups at 100 if I do my part with cast at 1500fps.

To the point: I want DST's.  MVA will sell me the internal parts, for a bit less than half the cost of one of their DST actions.  Am I better off, cost wise, to do that; or just buy one of the MVA complete actions and start from scratch?  To rebuild would pretty much mean gutting the action and starting over with internals.
To buy a new DST MVA; I'd go with a pistol grip action, and getting one built in the caliber I want for less than $5K would be difficult, and take about 18 months.

Thanks to all for their input.   

Rich

I realize you stated you want DST. However, have you considered a single set trigger? I have been told by people who know more than I do that you can convert a single trigger to a single set trigger on a high wall very easily. Might want to explore that option. 
Joe S

We had our big gun show here this weekend.  I got varying opinions, probably the best one, since I want a 50-90; is to just buy the MVA DST, PG action I really want, and go from there.  I got two quotes from the internet and someone here to stock it for around $1800 +wood.  A well known single shot builder in my area is sending me a couple blanks to look at, and says he can have the rifle ready to shoot about six weeks from receipt of the barreled action.

I have gotten sound advice from members here over the years, this good as well.

Thank you all,

Rich

If it was me I would opt for the original high wall.
Lee Gibbs Pres.ASSRA

My 32-40 competition high wall does have a stock through-bolt and a single set trigger but sports a flat spring and standard hammer.  It sports standard stocks, not a wide forearm and flat bottom buttstock.  I rest it on the barrel just in front of the forearm which allows for a consistent placement on the front rest.  It has a Green Mountain 14 twist barrel with a 'scary' bore.  
It has proven to be very competitive and has won its share of matches.  Here are some typical 200 yd groups under calm conditions. 

Bullet      Weight      Length      1:36      1:34      1:32      1:30      1:28      1:26      1:24      1:22      1:20
     Grains      Inches                                                      
BACO JIM512450       480      0.970      1.80      2.01      2.27      2.59      2.97      3.44      4.04      4.81      5.82
BACO JIM511500 FN      500      1.010      1.69      1.89      2.13      2.43      2.79      3.23      3.79      4.51      5.46
BACO JIM512515      540      1.100      1.46      1.63      1.84      2.10      2.41      2.79      3.28      3.90      4.72
BACO JIM511600 FN      600      1.220      1.22      1.37      1.55      1.76      2.02      2.34      2.75      3.27      3.96
BACO JIM511650 FN      650      1.300      1.11      1.25      1.41      1.61      1.84      2.14      2.51      2.99      3.61
BACO JIM511670M1 Money      670      1.515      0.75      0.84      0.95      1.08      1.24      1.44      1.69      2.02      2.44
BACO JIM511695C1  Creedmore      695      1.450      0.88      0.99      1.12      1.27      1.46      1.69      1.98      2.36      2.86

So what bullet length and what barrel twist for your 50 caliber rifle?
Gyroscopic stability factor has to be more than 1.4 and normally up to 2.0.
Long range shooters (1,000 yards) increase Sg up to 2.4 to compensate for drag.